Mocha clown behavior

[Unclebob]

I'm new to salt water tanks, with that being said my 10 gal tank has been up for a little over a month. I added 2 mocha clowns about 3 weeks ago. One is a little larger than the other, which I assume is the female or will become the female shortly based on my Internet fish knowledge. Long story short the other day I saw the larger one biting the smaller one, then a few min later the smaller clown would vibrate on and off for a whole on front of the other clown. I also saw the smaller clown biting the live rock on occasion, does any of this mean anything? Just curious, thanks.

Here's a pic of the clowns

 

[ccCapt]

They could be pairing up and the male cleaning the rock to have a clean area to lay eggs.