cylinder head install NEED HELP

i got a new head (assembled)from advannce auto. i got a new camshaft, new belts, water pump etc. transfered my old rocker assembly, put the new head on and the head was making a loud pooping noise,i took the valve pan cover off and noticed a few valve springs were sticking closed, random from cylinders 1-4,i sent the head back and the company said they tested it and it was fine and they said that valve springs dont stick,but i saw them when they were stuck so i dunno, what would have caused the springs to stick? did we mess up on the install or is it possible i had a defective head? maybe the rocker assembly was together wrong? anybodys help on this procedure would sure help me before we put the new one on so it doesnt f**k up again.