How far apart will the quilting lines be? If they are close together, the quilting will stop the fabric from shrinking more than the batting (which, if poly, won't shrink at all).
If the quilting lines are far apart, however, you could get enough fabric shrinkage between lines to cause a problem. If that happened, I would probably re-wet the entire quilt and block it to stretch the fabric back into shape, then add a lot more quilting lines. It would be a lot of extra work, though. Easier to quilt closely to begin with.
Edit: I do think it would be okay with quilting lines 4" or 5" apart on your pre-cuts. Most fabric will not shrink enough to matter over that amount.