Reverse seems to move start and end point

That's it really. I don't remember noticing it before but lately when I've tried reversing the direction of a ride by using the little reverse button it is also moving the start and finish locations to random places along the route it seems... at least not following any logic as far as I can tell. 

Any idea what might contribute to that behaviour? Has anyone seen it? Have I misunderstood what should happen?

Fantastic route planning site btw - thanks!!!