Chicks rolling in feed?

This is not my chicken's brooder, but just a little fun pen I put them for the first time today, in so I can sit in it with them and hand feed them, to bond. But these two chicks are doing this funny thing where they're fluffing themselves out and almost rolling in the food and in my hand. They walk normal, they act like normal chicks otherwise and it's the first time I've seen them do this. Is this weird or are they just playing?