I've noticed a fair few digs that Gervais has made to Peter Kay, especially in the Extras Christmas special. Obviously their was the catchphrase t-shirt, but also when he said in the Extras special about not wanting to be the sort of performer who performs a music video where he would sing a famous song and get celebrities to be in the video, but for the really famous people he would get lookalikes - which is what Kay and Matt Lucas did.
There was also the Dr. Who reference (Kay appeared in an episode).
I've heard Ricky say on XFM that he likes Peter Kay's stuff, but maybe over the last few years he's been annoyed by the same things I (many) have about Kay.