weird blocking behavior?

Question
I recently got my first hamster (at 21, oddly enough), and I love the cute little hammmyham. We got it a CritterTrail Two cage, aspen bedding, a nice balanced food, all that good stuff. She has decided to nest in the upper-most part of the habitat, which is connected to the bottom via a tube. That's all well and dandy, but as of yesterday, she has blocked the bottom of the entry tube with a good deal of packed bedding. She had brought a lot of bedding up to her nest, and she moves a lot when sleeping, so I thought it might have fallen in, so I started to pull it out from the bottom with my finger. She got curious, saw what I was doing, and started throwing down more bedding and packing it. I quickly stopped, and left her alone. Is this normal behavior? She brought food up to her nest, so I'm not worried about her starving, but she'd have to dismantle her blockage to get to her water. So, again, is this normal behavior? Or she just a neurotic or traumatized from her recent move or what? We've only had her 2 days now, and I already have grown quite attached, so I hope all is well. Thanks.

Answer
It's completely normal, my cage is set up in a similar way, and I rarely see my hamster come down from his look out nest. He has packed one of his tubes full, but he still manuvers fine. The hamster knows what it's doing, and wouldn't cut itself off from food and water.