Welcome to Spring - where a mile is no longer a mile

Is anyone else having issues with the Nike+ App and GPS accuracy?  On the last several runs I've done outside with my phone and Nike+ app, the GPS has been way off my winter running distances.  Today I ran a 4 mile route I run all the time.  It was fascinating.  None of the mile markers were where I thought they belonged.  Mile 2 should be near Lake Nokomis Rec Center at the top of the hill, not down the hill on the other side.  Mile 3 is at the top of a different hill, etc.  When I look at the map with pace breakdowns, it's showing me as stopping for the stop light about half block from where it is in real life. On my short 1 mile runs, suddenly I'm having to run around the block more times than in January just to run the same mile.  Sigh. 

I was positing some hypothesis for this issue with a friend.  It could be I'm actually not running as far because now I can actually run on the sidewalks, sometimes giving me a tighter turn radius, or making the circumference of my route a bit smaller.  I could also be a pain in the butt and blame some software update of either Nike, Apple or T-Mobile.  "Hypothesis" means "a proposed explanation that can be tested".  If you learn nothing else from this post, please, a hypothesis is not just "an educated guess".  Anyways, if anyone actually wants to try a controlled experiment and test one or more of these proposed explantations, let me know.  Otherwise I'm just going to live with it and keep running until my phone tells me I've gone as far as I wanted to go. 

Just for laughs, here's a breakdown of today's run.  I did a 4-miler around Lake Hiawatha. I ran around the block an extra time towards the end of the run, to make sure I'd done at least 4 miles by the time I got home.  I love that every mile split is faster than the previous (I start off really slow, takes me a while to warm up).  Mile 3 involved waiting at a stop light and Mile 4 involved waiting to cross some big streets with no light.  Also hilarious about this run, Nike thinks 10:41 is six seconds faster than 10:48.  I'm counting seven seconds.