Since you just got him or her on saturday, I'd say it's probably still relocation stress. That should go away soon with some filling meals
They can also get spooked by quick moving objects or people. Also loud noises can make them scared. It will still take some time before your beardie trusts you completely, but he/she will come around. I've had my guy for about 7 weeks now, and he gives me stress marks when I don't greet him when I enter my bedroom. It's like if his personal space is being invaded, then he stresses out and tries to puff up his beard a little ( he is starting to realize he actually has a beard, if you could call it that now lol). But once I pick him up and hold him for a bit, his belly goes completely white.