My GPS has been acting stupid lately. In Albuquerque recently I programmed in the Flying J just a few miles away but it took my like 12 miles around a loop with every light turning red. I was mad, but more at myself for getting off the freeway blindly following my GPS suggestions.
In Dallas, leaving the truck stop to go pick up my load which was to the west, GPS says get on the freeway going east take the next exit 4 miles up and go back west. Why do I want to do that when the westbound onramp is 200 feet beyond the eastbound one?
I think what happens is that it 'sees' the first road that will get you there and doesn't necessarily see the bigger picture.