Good news and bad news….
The good news is that it looks like it’s fixed.
The bad news is that it was fixed by disabling the cache.
I tested it this way:
First I disabled the cache in the config file. When I tried to edit the post it showed me the current revision of the post, instead of the original. I then reenabled cache in the config file. I edited the post, added text to it and saved it. When I tried to reedit the post, the added text was gone. I then disabled the cache in the config file again. When i opened the post in the edit window this time, the text added in the test above was there.
All this points (in my mind) to cache of at least the text in the edit box for the post admin page.
Do I need to open ticket on this? I’m not that familiar with Trac, so a point in the right direction would be appreciated if I do.
For right now, this is fixed by disabling cache. I’m not sure if I would really get any benefits from on a site as small as mine anyway.