It sounds like he is testing you. I'd stick with puttting him to bed as usual. Even if he grumbles provided he is not getting out of bed or crying, just ignore him and he'll likely realize that his behaviour isn't getting him anywhere and stop. The only other thing might be that he needs to shorten his nap. Although this happened with my dd closer to age 3 we found that if she had hr usual 2.5 hour nap during the day she would resist bedtime and not fall asleep until really late. when does he nap and for how long?