Was the orginal toolpath created in an earlier release? there is a enviroment setting that can be added to make the toolpath calculation in NX9/NX10 behave in a way that is more like NX8 and earlier.
We see differences of .001mm mostly on G02/G03 moves and most of this seems to be down to the rounding of numbers, I think they improved the way in which everything is calculated and as such you see these differences.
If the enviroment setting is set to on then the amount of changes you will see is minor or none but with it as standard if you do a file compare between a as saved program and a generated program the differences are in almost every line....
I hope this is of some help, I may be off the mark with your question but this is what I have seen.
Dave NX10.0.3MP13 NX11.0.1 Production TC10 Vericut 7.3,7.4.1,8.0.2