I used to take month or so long breaks between work assignments - work for two or three years, then break - and i would almost forget how to talk! I didnt go on vacation or anything, i just stayed home, caught up on sleep and exercise and some socializing. But living alone, and especially if i took a break from therapy, i remember feeling very uncomfortable with talking.

Also, yeah, a person will regress in therapy, if youre doing it right, IMO. Youre getting in touch with earlier feelings and trying to re-resolve issues.