It's completely normal. Chickens explore things with their mouths (like babies) and yes chicks will eat bedding. Mine have eaten dirt, bedding, bugs, etc.
It's only a problem if they eat a lot of bedding, or large pieces of it, and clog up their crops.
If you have not started offering them grit yet, now is a good time to do so. It will help them break down any pieces of bedding that they've eaten.