I have recently upgraded my beardie's tank to a 4x2x2. In the process I have also changed the substrate from sand to slate effect, and upgraded the UVB to a T5 (34").
Basically, he hates it. He's been in there for around 2 and a half weeks now, and he still has stress marks and sometimes a black beard. He also seems to be hanging around the corners of the tank. He's also shedding at the moment which may contribute.
Provide a hide in the warm zone and other in the cool zone, he'll choose the one he likes. He maybe a bit unsettled by there being more UV over more of the tank than he's accustomed to , I had a similar issue with George and Mildred my BTs when they young and I bought a 2ft 5%UVB tube to go overtop of their shared rearing tank .... they were not happy about this and spent a lot of time under their paper towel substrate trying to get away from the stronger UV than they were used to ( the breeder had them under 13W 5% elcheapo clone compact and household incandescent light globe for heat ). Changed to 26W UVB150 compacts and they were happier and spent more time basking and in the "open".
If you are in the northern hermisphere, it may be hormonal ( he's agro because his hormones are getting elevated with the onset of spring and the mating season ) , add the disruption of the changes to his digs , and he's unsettled.
Give him more time out to burn off some energy and more quality time , he'll settle in , but it may get worse as you move into summer (and he becomes uberhoney and starts having amorous thoughts about things he encounters (shoes, toys, feet, cushions, etc), but it wont last very long and he'll settle down once his hormones return to "normal".
Thank you! Today he has completely turned a corner and is happy and active so I think it was just the stress of the new tank. His face shedding is a lot better today too so I'm sure that's cheered him up a bit.