Why is Base saving automatically?

I am using LO 6.0.6.2 on Win7.

I discovered this morning that simply clicking Tables in the main Base window will give an odb file the current date/time stamp. And it does so again when I exit the file. All this even though I don’t tell the software to save anything.

I don’t recall Base doing this before. I don’t like it at all.

What can I do about it?

There is no setting to change.
What you can do as a user is to report this via the bug tracking system.

How to report a bug
https://wiki.documentfoundation.org/QA/BugReport