After I complete some dead lifts, and lower the weight back to the ground and begin to stand back up straight un-weighted, I feel an uncomfortable stiffness (EDIT)in my lower back at the top of my buttocks directly behind my hip bones on both sides, but not the center: ie. definitely not spinal pain.
Why would I feel this only after I stand back up straight from the low position without weight, but not with weight? That doesn't seem to make sense.
In other words, if I made the same motion with a 200lb dead-lift load for another rep (comfortably), I would not feel this same disconcerting sensation while loaded, but once I stand back up after the set is done, I feel like I am doing the "old, hunched over, man, 'ow, my back'", motion trying to stand back up straight unloaded.
It is not a sharp pain, but more of an unsettling sensation, and it is only experienced while I am in transit from being bent over to standing straight up again, and once I am straightened out vertically, the sensation quickly goes away.
Should I be concerned about this, or is this commonly accepted as a normal experience?