Fuel stain around intake valve

[squeaky.stow]

Did a boroscope during my annual and  one intake valve had a blue fuel stain around the seat. We are thinking this is from hand turning the prop to get the valves in the right position and some fuel in the manifold leaked in but just thought it was worth putting out for other opinions in case there is something more sinister going on. 
Compression check on all cylinders was all good and the white colour on one side of the valve is just reflection from the horoscope light. 
Sorry for the lousy resolution. I texted this photo to myself and it compressed it quite a bit. 

[carusoam]

Blue stains can’t exist in the heated cylinder of an operating engine….

So what ever you got there is relatively new, and hasn’t been there long…

 

How do all the exhaust valves look?  Lots of whole pizza, not any slices?

PP thoughts only,

-a-