What time does he generally nap and what time does he go to sleep at night?
My DD was definitely in the nap dropping phase at 2.5, and his behaviour does sound a bit like this, particularly if you've already been capping the nap for a while. There is a developmental leap for the half birthday that could be affecting his sleep but it may not just be that.
How many days a week is he in daycare? When my Dd first dropped her nap I kept it for a bit on the days she was at nursery as at is so much busier there, but with hindsight I just think that affected her sleep for the worse rather than the better.
Your DS may be showing different behaviours due to the developmental stuff but he may be not quite refreshed from his shorter night and dropping the nap (even if not every day) or capping it further might help with this.
What do you think?