DROP TRIGGER IF EXISTS increment unexpected GTID

Tested with:
Server version: 5.7.22-22-57-log Percona XtraDB Cluster (GPL),da86071, WSREP version 29.26, wsrep_29.26  
Server version: 5.6.40-84.0-56-log Percona XtraDB Cluster (GPL), Release rel84.0, Revision 4f77e2e, WSREP version 26.25, wsrep_26.25


PXC cluster with 3 nodes:
Cluster UUID: c334ed43-69ca-ee17-45d8-f817727f2ab0
note1> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin13.000004
 Position: 997
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-9
1 row in set (0.01 sec)

node2> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin14.000005
 Position: 1016
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-9
1 row in set (0.00 sec)

node1> CREATE DATABASE d1;
Query OK, 1 row affected (0.02 sec)
node1> use d1;
Database changed
node1> create table t1(id int);
Query OK, 0 rows affected (0.04 sec)
node1> CREATE TRIGGER trigger1 BEFORE INSERT ON t1 FOR EACH ROW UPDATE t1 SET id = 1; 
Query OK, 0 rows affected (0.02 sec)
node1> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin13.000004
 Position: 1567
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-12
1 row in set (0.00 sec)
node2> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin14.000005
 Position: 1570
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-12
1 row in set (0.00 sec)

node1> DROP TRIGGER IF EXISTS trigger1; 
Query OK, 0 rows affected (0.02 sec)

node1> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin13.000004
 Position: 1733
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-13
1 row in set (0.01 sec)
node2> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin14.000005
 Position: 1736
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-13
1 row in set (0.00 sec)
node1> DROP TRIGGER IF EXISTS trigger1; 
Query OK, 0 rows affected, 1 warning (0.00 sec)
node1> show warnings;
+-------+------+------------------------+
| Level | Code | Message |
+-------+------+------------------------+
| Note | 1360 | Trigger does not exist |
+-------+------+------------------------+
1 row in set (0.00 sec)
node1> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin13.000004
 Position: 1899
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1-2,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-13
1 row in set (0.00 sec)
node2> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin14.000005
 Position: 1736
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-13
1 row in set (0.00 sec)
node1> DROP TRIGGER IF EXISTS trigger1; 
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> show warnings;
+-------+------+------------------------+
| Level | Code | Message |
+-------+------+------------------------+
| Note | 1360 | Trigger does not exist |
+-------+------+------------------------+
1 row in set (0.00 sec)
node1> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin13.000004
 Position: 2065
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1-3,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-13
1 row in set (0.00 sec)
node1> DROP TRIGGER IF EXISTS trigger1; 
Query OK, 0 rows affected, 1 warning (0.00 sec)
node1> show master status\G 
*************************** 1. row ***************************
 File: mysql-bin13.000004
 Position: 2231
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1-4,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-13
1 row in set (0.00 sec)

node3> show master status\G
*************************** 1. row ***************************
 File: mysql-bin15.000006
 Position: 234
 Binlog_Do_DB: 
 Binlog_Ignore_DB: 
Executed_Gtid_Set: a27dba35-9634-11e8-a3e5-080027eb61ee:1-4,
c334ed43-69ca-ee17-45d8-f817727f2ab0:1-13
1 row in set (0.00 sec)