Incorrectly setting home

I was flying in my backyard last night and I thought it would be interesting to see how close the RTL would get back to the original home position. I flew it for a little while and let it RTL, then put a Hula Hopp out and pointed my Mobius down to see what it looked like. Between these two flights I did not shut off the quad. The first RTL worked great, but the second time I did it, it appears to have set the home position south and west of the actual home, about 10 meters. When I moved it over in loiter or Pos Hold, then engaged RTL, it flew South and West into some trees.

It doesn’t appear that HDOP was much over 2 during this second flight. Can someone tell me if there is anything they can see that would show why the home position was set so far off? At about 66% of the log, this is where i rearm and the home is set way off. the motion South and West to and from the new home never actually occurred. Is this just what happens when flying near tall trees?