I did this all the time when first starting Westside training. It never crossed my mind that it could be an injury, I just knew I was gonna be sore as hell from not using my low back like that ever before. Yeah, in retrospect I did way too much volume, but my back adapted. Just soreness like you're a newb all over again (do you remember your "1st week of ever training" soreness? I do. In my nightmares )
I like volume for the low back, but at a max weight your form WILL be compromised if it's a true PR attempt, so definitely some increased soreness as a result of not being in perfect posture.
On the other hand Tim's definitely right, if it's seriously asymmetrical or something else is going on you ought to be looking at it.