For some reason when I did Hip Raise on the left side, I might push a bit too hard with my arms that I twisted the upper left back muscles. It's not that bad, but a little annoying, especially I can always feel it whenever I try to stretch out my left arm. I wasn't quite upbeat this morning so I skipped the last 3 bonus workout and fast forward to the cool down session.
I had a little hard time to get up this morning. Maybe it's towards the end, and my body is aware of it.