Dwarf Hampsters, a question about aggressiveness?

We bought a male and female cambell dwarf hampster about three to four days ago, and they got along fine. The male (Tiber), was friendly and lovely at the pet store, and on the way home. Same with Lilly, the female.

Yesterday, I went to clean their cage (as we are planning to breed and sell the babies), Tiber bit me and then proceeded to act aggresive towards me as I continued to try and clean his cage.

Then, this morning I noticed that he was starting fights with Lilly, our female.

These fights usually started out with her or him, coming into their nesting area and then him trying to.. lick or bite her chin, to which of course she responded with a resounding "get away" actions and sometimes squeaking. Of course, he was persistant, and continued to try and do whatever it was he was trying to do, and it usually ends in a ball of two hampsters moving around and fighting, making loud squeaking noises and most of the time they get quite violent.

I have removed Tiber from the main cage, in a small holding cage until we are able to pick up another 10 gallon aquarium from the store.

Does anyone know why Tiber (our male hampster) starts fights like this? Could it be hes trying to mate with her, and when she says no, he goes into "hampster rape mode"?

We have (my husband and I) been trying to look around online, and most of them talk about close to birth aggressiveness of the female towards the male, but this isnt our case.

Any type of suggestions, comments, or help would be VERY MUCH appreciated!