Reasonably common from the people I have spoken to with HP 8'' 80 series housings. Everything just flexes so much the studs stretch. Get over to Outerlimits4x4.com and there is some stuff on there.
From what I have read you remove the stock studs, tap the hope all the way through the mounting face and screw in button head cap screws from inside the housing. Then torque those buggers right up with lock tight.