From a slightly different point of view......... My grandson even has diaper covers with skulls on them! And, no - I didn't make them. They are nationally marketed by the folks who have brought back cloth diapering. It's a fad, I guess. Not hurting anyone - but certainly opening their eyes. I don't think the babies are aware of what skulls may mean to us older folks.
You did a great job with your quilt. I can understand the hesitation the fabric gave you - but you went with it and it turned out great. The quilting did show up really well on the minky. The parents will be pleased and the baby will be snuggled in soft and cozy. Perfect!