Ah GPS, it has to be true! I have been reading about the shift in the magnetic north pole. This has been going on for many many years but recently has sped up. Scientists are recalculating the location and making necessary adjustments to GPS systems. They do this every 5 years according to one source I read. So, it is understandable that your device might send you down a path that is not really that far from the desired route. When I first heard of this movement I was thinking a few inches, or maybe a few feet a year perhaps. They say that in the last 5 years it has moved something like 31 miles! That could easily send you down someone's driveway if you are not paying attention.
A larger issue is how this will, and is, affecting the military especially in regards to GPS targeting systems. All that said, while it is not perfect it remains an impressive technological feat.
Disclaimer: I am not a scientist and do not believe everything I hear or read. This issue has popped up many times of late and I am not absolutely sure about any particular figures I posted. Google the issue and you should find enough information to make your own conclusion.