Tree Roots in PVC Sewer Line Possible?

[Paul Shannon]

I had a call from the PM for one of my rentals saying the sewer line was backed-up.  This house is only 30 years old, so assume that the line is PVC.  I was under the impression that PVC withstood tree roots.  Is it possible for tree roots to get into PVC?

I've had to replace old clay pipes due to roots, but am surprised to get this call.  Maybe there's an offset joint or crack?  

This property is in southern Indiana. It does get cold, but would be surprised as well if the line could freeze.