After destroying the prydwen with deacon I asked him to exit his PA. He jumped out in his undies. The outfit I had him equipped with was gone. I hadn't noticed when I unloaded all of his loot, but he was carrying some BOS uniform. I'm guessing this was so we could go "undercover" ( I chose to murder everyone without the uniform). Not a big deal except he was equipped with Kellogs outfit, which is pretty cool. So word of advice is to equip him with some clothes you aren't attached to.