had the head gasket done 6 months ago basically car has just sat in garage went to start it today when i was putting battery on i clocked some water seeping through the head on the right hand corner under dissy.anyway sarted the car up dissapeared after a while obviously with the heat.but once the car cooled down it was back again not much just seeping through will this affect the car.also there seems to be a tiny cap about a milimetre.any help gratefully received