I think I figured out how to tell a bad collet.

[knight_toolworks]

I had my 1/4" collet get all mushy it would take two to three wrench turns to get it tight. usually hand tightening and one turn is enough. So I replaced it and all is back to normal (yes I keep the dust out of it) there is no way for me to keep track of hours since I have 5 nuts and collets and use 3 of them all the time sometimes several times in a day.
I have been using this collet since I got my torque wrench so a little over 2 years.