Introducing two Gliders

Question
Hi Laurie,
Before I ask my main question, I'll give you some background info on my two gliders.
-Dobby: He is about 1 1/2 years old and neutered. I have had Dobby since Nov. 2007. His previous owner described him as an "alpha male". However, since I got him neutered he has calmed done a lot and is a very sweet little guy.
-Giselle: She is about 15 weeks old and I've owned her since she was 9 weeks. She is a fun, active little girl but hasn't really bonded to me yet.

Now, on to the question. Both gliders have been in separate cages and I switch them every week or so. I've been waiting to put them in the same cage together until Giselle gets a little bigger. (You can say she was the "runt of the litter". The breeder even kept her an extra week to confirm she was healthy.) Lately, I've let Dobby climb on the outside of the cage to interact with her, but still have the cage barrier. They seem to enjoy this and are always chattering, which I have interpreted to be a good thing. Sometimes Giselle will even bark at him as if to get his attention and he'll come running over to that side of the cage. However, they are expressing one behavior that I'm trying to decide is good/bad/normal.

Both of them reach through the bars and grab at each other. However, it's not a violent grab, but a very gentle grab. They will even gently nip at each other's fingers and tails. The thing I find interesting though, when one does it to the other, the other doesn't fight back. Last night, I think one nipped too hard, because I heard the other squeal a little. But they still didn't fight back. (Sorry, I couldn't tell which one squealed.) Nether one seemed injured.

Should I be worried that they won't except each other as cage mates or is this normal?

Answer
Hi, Lori:

It sounds like all is going well and sounds normal.  They sound interested in each other.  I would be switching their sleeping pouches and not switch the cages and I would do this every other day at this point.  Make sure she is at least 3/4 the size of the male.  

As far as trying to interpret their behavior, it sounds normal at this point.  Unfortunately, they could still have a problem once there is no barrier and there is just no way to tell.  

When you introduce them, do so in a completely neutral area that you can control, like a bonding tent or a bathroom and stand ready with a towel to separate them if they begin to fight.  Best of luck with these two.  

Laurie