I didn't really think about this until someone started the thread complaining about the picture of the ATL B skyclub on delta.com, but when I access delta.com from my main browser (chrome on OSX) I always get the same background picture ("Fly Premium Select"). It's been this way for... weeks at least, maybe months? I just never really thought about it until now.

Clearing cookies or logging in didn't change anything.

If I load delta.com on safari or firefox, I get the normal behavior (different background pictures on a rotating basis).