Safari 4 glitch?

I can't explain this. I can't even duplicate it so I'm completely stymied. Here's the issue: several people have reported experiencing a minor display issue with Safari 4. It shows up particularly in comments and involves mis-positioning of the Gravatars. Here's what it looks like:

See? That's pretty messed up, right? But here is is from my machine, perfectly aligned:

Yes, both are from Mac OS X. My first thought was that it has to be a window size issue, but no matter how I resize it, I don't get this. Display? How could that matter?

Maybe Safari 4 isn't Safari 4? I'm using "Version 4 Public Beta (5528.16)" - if you get munged results (try http://aplawrence.com/Unixart/more_backup.html for the page displayed here), could you check your version and let me know in comments or by email?