My younger male rat has always chirped more than my other, ever since I got him. He doesn't seem to be distressed, more so like he does it when content, such as snuggled up/sleeping, or getting attention. It's not excessive, it's just my other rat has never really made a sound while my other seems to be talking my ear off sometimes! He is going for a general vet visit soon, but I don't think it is health related. Should I be concerned?