oracle 11 g VKTM detected a time drift？

Tue Dec 26 00:02:25 2017
Archived Log entry 22015 added for thread 1 sequence 13472 ID 0xffffffffffe006b9 dest 1:
Tue Dec 26 01:00:00 2017
Closing scheduler window
Closing Resource Manager plan via scheduler window
Clearing Resource Manager plan via parameter
Tue Dec 26 01:56:23 2017
Thread 1 advanced to log sequence 13474 (LGWR switch)
Current log# 1 seq# 13474 mem# 0: +DATA/erpdb/onlinelog/group_1.261.848792895
Tue Dec 26 01:56:24 2017
Archived Log entry 22019 added for thread 1 sequence 13473 ID 0xffffffffffe006b9 dest 1:
Tue Dec 26 03:11:29 2017
Warning: VKTM detected a time drift.
Time drifts can result in an unexpected behavior such as time-outs. Please check trace file for more details.
Tue Dec 26 03:50:54 2017
Thread 1 advanced to log sequence 13475 (LGWR switch)
Current log# 2 seq# 13475 mem# 0: +DATA/erpdb/onlinelog/group_2.262.848792895
Tue Dec 26 03:50:55 2017
Archived Log entry 22023 added for thread 1 sequence 13474 ID 0xffffffffffe006b9 dest 1:
Tue Dec 26 05:30:23 2017
Warning: VKTM detected a time drift.
Time drifts can result in an unexpected behavior such as time-outs. Please check trace file for more details.
Tue Dec 26 06:02:08 2017
Thread 1 advanced to log sequence 13476 (LGWR switch)
Current log# 5 seq# 13476 mem# 0: +DATA/erpdb/onlinelog/group_5.263.848792895
Tue Dec 26 06:02:09 2017
Archived Log entry 22024 added for thread 1 sequence 13475 ID 0xffffffffffe006b9 dest 1:
Tue Dec 26 06:35:29 2017
Warning: VKTM detected a time drift.
Time drifts can result in an unexpected behavior such as time-outs. Please check trace file for more details.
Tue Dec 26 07:29:09 2017
Thread 1 advanced to log sequence 13477 (LGWR switch)
Current log# 1 seq# 13477 mem# 0: +DATA/erpdb/onlinelog/group_1.261.848792895
Tue Dec 26 07:29:09 2017
Archived Log entry 22025 added for thread 1 sequence 13476 ID 0xffffffffffe006b9 dest 1:^Croot@erpdb1:/u01/oracle/app/oracle/diag/rdbms/erpdb/erpdb1/trace#