Does hair transplant cause my hair to be gray in some areas?

I had the surgery a month ago and started seeing gray hair in the doner area more than usual. It's noticeable, before i had 1 or 2 gray hair here and there but now it is very clear that i have gray hair. I asked my doctor if the vitamin I was given caused this but he told me there is no side effects and i am the first person who said this. Do you have any advice for me. I am a little worried about this, i tried to fix something now another thing is coming out of no where.