I think its most likely a lifter tick if the engine hasnt been run in a few months. How did it run in the few moments that it was running? Personally I think that if you had valve to piston contact the engine would not run good. To be on the safe side you can check the piston tops for contact but i doubt you will see the valves good enough to determine if they were damaged. You would have to check the top of the piston for any marks.