Well first of all your hook is not 4.0...it's a 4/0!
You can't win'em all....pull harder next time try to keep it outta the kelp as much as you can. If it does get buried again....then try sawing back and forth, if that doesn't work try free spool'n it a little....check the length of your leader, make sure it's not too long. If it is....your mono/floro will not cut the kelp.