I might be wrong about this but not all ankle locks require a tap before it hurts. Straight ankle locks hurt like hell but you don't have to tap (eventually it will break your foot, but he has to be fully extended and if you "have your boot on" you can avoid that). Heel hooks, however, tap when you feel pressure in your knees.... if you want to keep your ACL/MCL attached.
Hmm maybe you're right because I didn't feel anything but he trainer was like "you gotta tap!" and I was like "...why?" He was doing a heel hook.