Im not going to say yay or nay here however will suggest you talk to the parents about what the baby will be sleeping with in their crib. Parents today (myself included) are advised AGAINST "tucking" infants and young children in while they are still crib age do to SIDS (sudden infant death syndrom)!
My suggestion...make a quilt that is 48x60(ish), this size makes a GREAT quilt for the parent and baby to cuddle up under TOGETHER hanging out on the couch or in a chair, its also a great size for tummy time even when babies start to crawl around. It is a great size even for my seven year old! This is the size I have started making and EVERYONE loves them because they are so much more versatile than just a 28x52 (crib size measurments)