I noticed this a week or so ago, I assumed it was a Opera 9.5 bug, but, It appears to have persisted, and i think there was a TinyMCE change around that time too.
When writing a post using TinyMCE under Opera 9.5, pressing enter creates a new paragraph above the current one, Here is the result of me typing:
1 {enter} 2 {enter} 3 {enter} 4
4
3
2
1
Does not appear to work after reverting to [7678] (Which means i was running TinyMCE 3.0.6) which suggests it may be a Opera 9.5 bug, or something in the way tinyMCE expects Opera to handle. Just getting this out there so that its a known bug.