playing or fighting?

As some of you may know, I recently adopted a new kitty from the shelter as a compainion for Kina. At first, I was faithfully keeping "new kitty" (no name as of yet) in the bathroom- letting Kina get used to his scent. However, curiosity eventually got the better of me and I let him out to see what the reaction would be. Well, for about a day and a half Kina would growl and occasionally hiss at him, and New Cat would just walk away and look at me as if asking, "what's her problem?" We are now on day 5 and it seems like a success story! Kina and New Cat both lay on me on the couch together, touch noses etc. and there is no growling or hissing. However, I do notice them occasionally engaging in what looks like "kitty wrestling." (but the ultimate fighting championship type) There are headlocks, kicking, and biting involved and both cats are letting out what sound to me like mini battle cries. These bouts are usually started by Kina calmly walking up to new cat and poking his paw. Since these two are my first kitties, I have no clue how kitties play together, much less fight each other. Is this behavior something that I should be worried about or is it totally normal? Thanks in advance!

It's playing!! Don't worry about it!!

Sounds like they are playing...mine are always hollering out here and there...my youngest is alot smaller than my older 2 but he still runs and tries to play...he has no fear in the world...i think if they really hurt each other, there would be growling or you would just be able to tell....congrats on your new kitty though!!!