Yeah, I hooked him up. Sometimes there's discrepancies, if a mod takes out what they deem as an inappropriate avatar it can screw up the person getting another avatar back up on occasion, not sure why that is. And though I've put down a french fry reading some of your posts, in the end it's just a fat, slighty asian looking middle aged man in a pink training bra with a come hither look. That's just Sherdog. It's not like it's a Rosie O'Donnell avatar. Also, if you've been a platinum member and go defunct for awhile, the 135x135 vs. 100x100 avs transition back might have a burp, though it doesn't happen often. If you get carded, you can also lose your avatar, you're supposed to. If you have custom text, it can sometimes block the cards from being visible, so your avatar's gone and you don't know why - (if you have a rebellious nature, maybe Josh Crosscheck your recent post history with the User Rules sticky and see if anything lines up).
Other than that, if you're just hitting the 250 post count, as has been said, just hang in and let it ride, it'll kick in.
If you think you're having problems outside those I've posted, pm me or post here in the support forum and we'll get to it. Rosie O'Donnells, you're on your own.