Hello to all hamster lovers! Emotion: wave

Am currently at a loss when it comes to my little hamster.

She was always very lively, busy and often a little wild, but she has never bitten on purpose ...
Recently, she attacks immediately any hand that comes into her area. Even if it is only in front of the cage and I holds out my hand.

I do not get her change ... She's never really defended her territory, I'm not using a new soap, etc. I also let her out enough, I just don't understand what's happening.

She is not sick and if she's bitten, she'll immediately let go again...
What would you do? I must sometimes long into the cage to give her food or when she's turned over her wheel.

Am a bit worried and I am grateful for any advice!

For how long has this been happening? Maybe she was just in a bad mood? Has anything scared her lately, or has there been any change in her environment that now makes her feel insecure and protect her territory?