Hi Sabine, I don't know if you realised, but you didn't post this in the feeding problems section! You'd get more views in there
I think you answered your own question, if she's paler it's very likely she's in the 'blue' phase and is just getting ready to shed. A LOT of snakes refuse food during this time, so don't worry. Missing a few feeds won't harm her in any way.
One last thing, just offer food once a week or however often you normally feed as opposed to every day