Don't you hate when that happens...

Helped with a stock 4 cyl Vega engine swap. Engine out,new one going in. Installing pressure plate. Car owner yells "how tight?".Not really thinking about it,replied"snug" . To me ,30 to 40 ft.-lbs. Him,not really mechanically inclined,"snugged them". Drives off. Two hours later,get "the call". Tow it back,sure enough, the bolts backed off. WHOOPS....