If you ever spot Spam (either in the forums, or received via forum direct message) please use the Report button at the bottom of each post to make sure a Moderator can handle it quickly. Thanks for your help in keeping things running smoothly!
Nothing. various levels of cacheing (which are actually applied inconsistently across some pages, stupidly) mean that it can take a while (sometimes even up to a few days) for images to be refreshed in our CDN correctly. Give it time.
Funny thing is, I deleted the old avatar the other day to give the servers chance to clear, and it disappeared instantly, from both my 'My Account' profile and my posts. So today I uploaded a new one, yet my new posts appear with my old avatar. Go figure.