Mowing LX280 PTO Problems

[Gearz]

I have replaced the electric PTO last year and and about 10 hours after mowing i disengage it and it make a metal on metal sound then it goes away when the clutch stops spinning,the old one did the same thing and i can see that it is coming to rest on what looks like another piece of metal does any one know why it does this and if it is normal or is there a fix without having to replace another $150 part? And yes i torqued it to 55 foot lbs per instructions.