RunKeeper Accuracy and a Deer on my Walk

Yesterday, I was walking one of my normal routes near my house and heard some rustling as I passed over a bridge on Bluff Springs (Southeast Austin).  When I looked down, I saw a deer!  It's not the first time I've seen deer in this area, but it was still very cool.  It's one of things I enjoy about walking in that area.  I snapped a few pics with my phone before she took off.  See if you can spot her in the one below:

After she ran off, I walked to what I believe is the 1.5 mile point and checked RunKeeper since I was trying to walk an even 3 miles.  It had me as having walked 2.72 miles!  This is the first time I've ever noticed a discrepancy like this.  I stopped, restarted my phone and the app, then walked back.  I kept checking it on the way back and it was fine up until one point when it seemed to lose the GPS signal a few times.  Then, the distance shot up some.  When I checked RunKeeper, the maps had me on my regular course but also had me in some areas I never went.  I removed the maps and edited the distance to 1.5 miles for each leg.  It's a bit frustrating because I really need it to be accurate so that I can measure my distance and achieve my goal.  I read their FAQs and they had some recommendations on how to improve accuracy.  I downloaded an update and made sure all the settings were right.  Later I ran a couple of miles with my running group and it was accurate.  Since that walk was the first time that I've noticed any issues with the distance, I'm hoping it was just a one-time occurrence.  In any case, I'll be keeping my eyes on the maps after runs/walks, since those seem the best way to determine if I am being properly tracked.

Exercise Log:
1/2: 3 miles walking; Running group (2.37 miles) + drills @ TSD; TotalGym John Carleo 6-day training (Day 1).  Total Miles for the day: 5.37