Fantail, yes, me too! I am on Day 39 now and for the past week I have been feeling really blah and antisocial. I am also fairly social and felt awesome for the first three and a half weeks but the last one has been a bit of a downer.
I find myself even wanting to leave work early (and I like my job and who I work with) to go home and crawl into bed with a book and be alone. So unlike me.
Also finding myself getting snarky and testy with people. Snapped at my mother and then a friend last week for relatively minor irritants that I normally would just ignore.
Anyway, glad you posted about this because I was starting to feel a little alien myself.
Hope it passes soon!