Cockers are prone to warts, but typically get them in middle or old age, not when as young as Harry. If it's a wart it shouldn't be of any concern except that if he's knocking it and then licking it may become infected and then might need to be removed.
I wonder if it could be a Histiocytoma? They are harmless lumps that are fairly common on young dogs. Sometimes they just disappear after a while, but sometimes they may grow bigger or become an irritant, and then have to be removed. If you do a search on here for Histiocytomas you'll come across a few posts about them.
I think if Harry was mine I'd have it checked by the vet in the next week or so if he continued to find it irritating and licked it a lot.
