Nope, no need to call ahead. When you check in at the podium, let them know about the birthday then.
The only reason you should call ahead is if you want to order an 8" cake. You can get a 6" cake there without pre-ordering if you want to. Most people prefer the 6" over the 8". The 8" is really nothing special to be honest. Instead of a cake, you may want a dessert, and they'll write "Happy Birthday" on it and such.

I suggest the Chocolate Moose!