I'm sorry that no one got back to you.
It might be that there was a significant increase in data to be collected and the Base Monitor host struggled to keep up, but quickly did so within the 15 minutes and so returned to normal.
If it happens regularly then it can be concerning, but can also indicate that a regular task is contributing to the problem. Can you send the SQL Monitor error log files to support at firstname.lastname@example.org
and quote this forum post in your email.
https://documentation.red-gate.com/page ... d=20743048