This is probably a daft question, but at what age did your LO stop having daytime naps? I've been talking to someone at work who has said their DS was still taking naps up until starting school!
My DD (2.4) in the last month seems to have stopped wanting naps, even when I do all the usual 'tricks' to get her to sleep (long drives used to be a favorite!). I didn't see a problem in this as she seems happy enough (not grouchy/clingy/unwell etc) and sleeps enough at night, but my colleague has said that children need sleep during the day and I should be limiting her night-time sleep so she will want a daytime nap 
I think he's barking, but now he's planted a seed of doubt in my mind, I'd thought I'd ask your opinions!!