Piston to valve contact

When I pulled my head this morning for a headgasket issue I noticed where some of the intake valves had slightly hit the pistons... I checked the clearance after I put in the 188/220 and I was coming up with roughly .070 of clearance on each intake measurement... Where could I have gone wrong and how could this be? I measured at three points before and after TDC by running the valve down till it hit the piston with a dial indicator on the rocker...