Thats one GREAT feature Modo has. It saves the UV Mapping when U subD the model. I found this out the hard way. I used to UV Map my Armor Cars after I cut it up and it makes it SOOO HARD to UV Map. Now i UV Map it before I cut up the model to make the hard edges, cuves, bumps, etc etc, and it keeps the UV Mapping without any issues.

As Tashas59 said, show an image of what U found and see where is the issue.

Thankx