There is nothing wrong with the pull -- not that 135 could hurt you pulled wrong anyway. But you have a very bad habit of lumbar overextension at the top, shoving your good spinal position into a bad anterior pelvic tilt. The secret to spinal health: Keep the damn thing RIGID while it's loaded, even if it's in the wrong position anatomically. You can tolerate a bad mechanical position under a submaximal load IF the intervertebral relationships remain absolutely constant, but when you move the discs and facet joints around under load, bad things happen.
I think I've already told you to stop doing situps and back extensions for this reason. Not everybody can tolerate wiggling their spines around.