All tucked in and tuckered out

Sam generally is very good as we are reading him books and getting him ready for bed, but after we put him in and say it's time to sleep, he usually lets out a cry and stands up. Now, he only lasts about 5 minutes and then quiets down. The other day Dave experimented with tucking Sam in under his blanket and it worked like a charm! No getting up and no crying. Was he just waiting all this time for us to figure out he likes to be tucked in? We don't know, but it seems to work so we're sticking with it.