I had a side banner that was 106 x 306 px. The rule says, combined, forumsets can't be any bigger than 400 x 325 px.

Why was I warned? It was within the limits... is there a different rule for side banners and, if so, has it been posted yet so I can at least resize the graphic?

Did you have a signature too or anything?

As for why you were warned, it is recommended that you create a ticket regarding the matter.

I had the banner and a text credit in my ForumText plus one Valenth adoptable in my signature. That might've taken me over the limit but not so much so that it warranted being warned, in my opinion...

Just a sMail and I would've fixed it.