Preliminary results: out of 6 times picking it up on a completely smooth plastic surface, 4 times it reacted and released itself almost immediately without any resistance. 2 times it stuck for a while and I had to tug it off, but released itself from the surface without any apparent harm. There was no change in behaviour to indicate injury after all the pick up attempts.
Currently euthanising it and I'll check the mantle for any signs of injury or bleeding tomorrow.