If you have another network, you can check the delay
No. I could not see the log entry at 13:30, untill 13:54.
The entry at 14:00, did not appear until at 14:07.
Another thing I'm curioust about is that I have difficulty in believing that I'm getting the same two "Source IP and/or VLAN mismatch" events every 30 minutes, precisely on the second, for the last month.