I think Diluted meant to say when he retested his 3RM he hit a PR. Maybe not though, but you're right Mikeee, you're not supposed to be going for a PR during the regular programming.
BUT, this is what CT always preaches. Some days you don't feel great, so you go and do your work needed for THAT DAY and be done with it. Other days you might feel like a million dollars, and you KNOW you are much stronger than you usually are. I'd say it's probably alright to go for a PR on those days when you know you're going to kill it.
I'm just starting week 4 tomorrow, and OP, I can't say I feel what you're feeling. Maybe you go to hard on the assistance work, or you just haven't built enough work capacity for this frequency of training. Are you doing the neural charge sessions? I was on winter break from college this first 3 weeks, and I took advantage of having nothing to do and split the majority of my days into two sessions. I think that helped a lot