love nibbles or agression

Question
I recently got a new pet rat named Masumi. She is a bundle of joy, but im new at taking care of rats and am curious about a new type of behavior that she has recently started showing. sometimes when I take her out of her cage I will let her roam about on my bed which has pillows all around it and I guess she may see it as a "jungle gym" im not sure though. However when I get near her she begins to move really quickly like she's afraid of something and she'll come up to my hand and bite quicly (not hard enough to break skin its more like a rough nibble, but im worried if her bites will eventually be hard enough to break skin). Is this type of behavior just simple exploring and love nibbles or is it something more agressive?  

Answer
Actually Christina you are right. It can sometimes be love nibbles or just trying to tell you to let me play some more lol. My hamster will nibble on my finger to tell me he wants to stay outside of his cage longer if he's not finished exploring his surroundings. If she starts constantly biting you until you bleed and it hurts than she is showing aggression, but right now I think she's just getting used to you. Generally I talk to my hamster before I move towards them. A good treat in your hand will also help them come to recognize that your hand isn't a bad thing. :)