Tame dwarf hamster suddenly biting

[SanguineCane]

Ive had my dwarf hamster, Wilbur, for about 2 months now. The taming process was really easy and I play with Wilbur every day.

Out of nowhere a couple days ago, I put my hand in Wilbur's tank to see if she wanted to play. Usually she climbs right into my hand which is what I thought she was going to do this time. Instead, she walked right up to me like she normally does and bit down hard on my finger. She didn't even sniff first. This wasn't just a nibble either. She drew blood. Since then, Wilbur has been biting me every time I give her an opportunity. She's not lunging at me and she's not acting like she's scared either. Just coming up to my hand and chomping down.

I'm worried that something might be wrong with her or that I've done something to upset her. She doesn't seem to show any signs of sickness or malcontent other than being a little picky with her food. She's my first hamster and I really love her. I hope I'm not doing anything wrong.

This is her tank setup - Its a 75 gallon tank (880 square inches) with 3-5 inches of paper bedding depending on where Wilbur decides to relocate it. Theres a large hide in the corner that she likes to sleep in on one side of the tank. There are tubes to explore. She has apple wood chew toys and an 8.5 inch wheel to run on. Id love to know if I'm doing something wrong.

I just don't understand why a normally sweet hamster would suddenly start biting to the point of drawing blood. I'm scared something is wrong. I've been keeping an eye on Wilbur but if things don't improve, I'm going to take her to the vet.