Question.…… / story GPS not allowed at the following race

Like many a fell runner Johnny likes to tuck in behind the person in front. Mist is down, and he and whoever it is in front have a blinder, hitting all of the lines perfectly. Johnny was really grateful that the person in front was such a good navigator / knew every inch of the course so well. Person in front used a GPS, Johnny has no idea that he did.
Person in front has broken the rules, and not fessed up, so we don't like him.

What about Johnny?