It can indicate a valve leak. Better safe then sorry. Try taping the valve open and closed a few times it may just have a peace of carbon on it holding it open. Taping it open and closed will brake the carbon up.

A pressure test to me is looking for a crack in the head to the coolant passages. A vac test to me is applying vacuum to the compression chamber and testing for valve to seat problems. Maybe thy have different methods then what I'm used to.

You could also just lap them if thy are not in bad shape.