Great news about the night sleeping! And even if he is only getting 1.5 hours nap a day on the w/e that is still 12.5 to 13 hours per day which is where he "should" be at. My dd is only now going to 2 hour naps with me on the w/e so don't be surprised if that doesn't change too much for the short term--too much excitement I guess. But I would stick with the new schedule or move the nap ahead 15 minutes if you don't want bedtime thrown off too much.
