Well if it sticks again I would seriouly look into having a valve job done on the cylinder head. The valve guides are probably worn or you have a bent valve. If it stuck once you need to figure out the "why". Are you getting oil up to the Rocker arms? This is easily checked by running the engine without the valve cover on. If you have oil to the top Good. If you don't you need to get that fixed first and then go from there.
