Dish changed directions?

I just noticed today that my V2 dish has changed directions from NNW to SSE, basically a 180 degree flip. I haven't paid attention, so this could have changed weeks ago and I might not have noticed.

Facing NNW, there was no obstruction, but SSE has introduced the edge of my upper roof into the obstruction map, even though it says there are no obstructions.

Is this normal?