Source Dates replaced with todays date

[NextPage66]

I always like to see the source date in the gutter. It is very helpful and useful.
Most of the time I see the dates but there have been times when i am moving between tabs and notice that the date is not visible. I usually close the member and reopen it to get the source dates.
However, I made some changes to a member yesterday and after I pressed the save button I noticed the dates were not there. I closed and reopened the source and all the lines now have yesterdays date. I think there is not an issue as long as the source dates are visible. But if they ever disappear I cannot save my changes until they decide to show up again. If I click around and come back to the source file they will sometimes reappear. This is a big deal. Not user friendly to have to monitor that so closely.
Now I have to spend a few hours getting the source dates back to their original date.
What would cause the source dates to disappear and reappear in the gutter?

Example from today:
I opened a compare on 2 source files.
Pic #1 shows the first time I opened them and it is missing the source dates on the left side.
Pic #2 shows the second time I opened them and it is not missing the source dates.
All I did was close the compare and reopen it.

This issue is not just with compare function because it has happened on just regular source viewing also.

Thanks for any help.