If you were logged in, then it probably was just some weird, random anomaly. If it happens again though, I would report it to the site feedback forum at http://eq.zam.com/forum.html?forum=3 so a developer will see it. Most don't browse the game forums much unless they happen to play that game, but they do check the feedback forum, and even if they don't the customer service people do, and will set up a ticket for it.
Everyone just assumed you weren't logged in, since you will see ads, if you are not, and you hadn't mentioned that you were.
Hope it doesn't happen again, but if it does, feedback forum should get you a developer / admin response, and hope this helps some.
EDIT: Also, if you just recently signed up for premium, you might want to clear you browser cache, just in case that was the cause (unlikely, but could of happened).
Yther Ore.
Edited, Dec 23rd 2011 2:39am by Yther