Lots of plants (I seem to notice it more on trees and bushes) have leaves which are a different colour when they first develop. Mostly, they’re reddish. Coloured from growth hormone which is then recycled by the plant leaving the leaves green. Some trees have been bred to keep this colouring: copper beeches among others.
I just noticed that hazel seems to do similar. But instead of various shades of red, the growing leaves have a greyish area. I went back the day after these pictures were taken. All the leaves were green with no trace of the grey.