You know, I think every kid is different and a lot depends on what they are exposed to. I'm a painter as a hobby, so colors are a big part of how I share my world. I think that played a role, along with signing, in DD knowing her basic colors very well ridiculously early. The ABC's, however, at 2.5yrs she really can't do... well, much at all. Or count past 13 reliably. But I haven't really pushed any of these, it's just that colors were "easiest" for us.
So, I wouldn't worry about it. IIRC, being good with colors is a 3yr milestone. You can always check with your pedi about it, but I doubt it's any cause for concern.
(Also remember that there is a BIG difference between "point to the blue one" and "tell me what color this is". The first one requires they understand what the color blue is and can move their hands and point. The second one requires they understand the color AND can communicate the word - those are two different skills that usually take a while to combine.)