What happens when you smooth the low poly in maya, are the UV's screwed up then?
Just that I've had a couple of things "alter" the UV's after emoothing that I thought would have preserved the UV space but didnt. Untill I switched it off in the smooth Mesh options.
Maybe theres an option in the sub d approx (or it might derive it from maya?)
"No pressure, no diamonds" Thomas Carlyle