This happens a lot to me in KSP, the lander tends to slide all the way to the bottom of the slope. Most of the time it's okay, just need to tweak the dampeners on the landing legs a bit ;)
EDIT: I went to re-watch the moment on youtube and it does seem like the lander moves slightly to the left!
EDIT: I went to re-watch the moment on youtube and it does seem like the lander moves slightly to the left!