Help with my two fancy mice?

I have two fancy mice, both female. I've had them for only about a month and a half now. I was just sitting on my computer, and all of a sudden, I hear a bunch of squeaking. I look over to see that one of them is chasing the other around the cage. When I got them to separate, the one that was being chased looked a little shaken up. They never showed any signs of aggressiveness towards one another, but they usually play together and are very nice. (They even managed to find a way to run on the wheel together.) Were they fighting or playing? If they were fighting what can I do to keep something like that from happening? Also, they only have one food bowl, and one hut. Could that be the problem? Is one getting overly territorial? Thanks in advance for your help.