Main Bearing Clearance

Make sure the saddles of the block and caps are clean. The bearings may be not seated all the way.
I like to torque all the mains to specs first and then remove one cap at a time to plastigage. That should seat all the bearing shells and keep you from getting false readings. Rods can be done one at a time. Remember to lightly tap on the bearing caps with a brass hammer to make sure they're seated properly before you do the final torquing.