PB Labs can have a patch of white fur on their chests.

From http://www.akc.org/breeds/recbreeds/labdoret.cfm

Color

The Labrador Retriever coat colors are black, yellow and chocolate. Any other color or a combination of colors is a disqualification. A small white spot on the chest is permissible, but not desirable.

Who knows!! Wish he could talk!

Thanks