Small Head Size

Has anyone had a baby who's head measured small? Our 4 day old newborn had her first doctor appointment and her head measures in the tenth percentile. It does not look small to me or oddly shaped as she is a smaller baby at 6lbs 14 oz.They never mentioned her head being small in the hospital and she is doing well with all other development (breast feeding, reflexes, etc). The doctor told us not to worry too much about this right now because of how well she's doing otherwise. I'm really freaked out about this and was hoping someone else has experienced this and had a completely normal child as they got older.