Maybe she meant "redundant foreskin"? According to a video produced by DOC, redundant foreskin was meant to mean the foreskin that extended well past the glans of the penis on a newborn. For some odd reason circ-happy doctors thought those boys were born with too much. They've since discovered that, depending on how large the penis grows as an adult, even infants with quite a bit of skin at the end can end up with just the right amount to cover the adult glans.
Another case of medicine inventing a problem in what should be a normal situation.
Maybe it's time you updated your MIL.
Get her to watch this video (WMP, streaming) http://www.doctorsopposingcircumcis...OC/prepuce.html
(WMP, download) http://www.doctorsopposingcircumcis...NTSC_256k_D.wmv
(thanks again Sunflower mommy for finding those links