A Rite of Passage?

Logan has been wearing pajama bottoms without a shirt to bed for a couple of weeks. (No big deal.) But a few nights ago he started sleeping in his underwear. He was all ready for bed. Actually he was already in bed, when he suddenly decided he needed to peel off his pajamas and sleep in just his underwear. It was funny to watch him squirm out of them without getting up, but he did it and was quite proud of himself. Tonight he just got undressed and climbed into bed without giving pajamas a second thought.

So who is this little boy who has never even wanted to wear pajama shorts to bed and is now wearing just his underwear? Is this a sign of growing up? Because if it is, I'm not sure I'm ready for it.