Michelle, I think that age is a fairly significant developmental stage. Babies this age become a lot more aware of what's around them and are more active - thus they aren't really interested in sleep (don't I know this one! *L*) and would rather stay up and socialise! Alot of babies are teething around this stage too, so it can throw their routines out of whack. Maddy only really began to get sorted with her sleeping at this age; but I'd suggest just going with the flow.

He will sort himself out but make sure you listen/pay attention to his tired signs. If you follow his cues and put him down for naps (even if they are different to what he used to do) when he exhibits these signs then hopefully he'll soon fall back into a regular sleeping/napping pattern.

Good luck hon! Glad to hear he's still sleeping so well through the night for you.