Blue dryish mark on kittens nose

I went to visit the kitten I’ll be bringing home next week & he had a blueish mark on his nose (he was not born with it). The breaded said he got it from getting into the adult cats food. Why would that happen? Is this something I should be concerned about?

Hello!  Despite changing to a better screen and doing a lot of zooming, I am unable to get a good enough picture here to understand what is going on with this adorable kittens' nose.  However, it would be strange for adult cat food (when given as opposed to kitten food) to turn the nose blue.  I would therefore suggest that when the kitten is handed over, you arrange to meet at your vets' for a consultation.  This way, any concerns can be addressed at the time of purchase by a professional.  Most good breeders would agree to this.