What does this usually means?

so I wanted to try a new exercise called pendlay row ( ) people say this exercise if done improperly causes low back pain. I recorded myself and in the first set i felt a slight lower back pain but i continue doing it and finish 3 sets and i felt normal to be honest. just a little pain in the lower back. i finish my entire workout with a little pain. two hours later im at home sitting down in my chair writing this with more lower back pain (increased in pain). I know sarno says that pain during and after can be tms. but 2 hours later the pain increases just from sitting? my form in that video is not even that off. I have to admit, i was worried about the exercise for days but i wanted to try something new, even if people said it causes back pain if not taken with good form