My 10 month dd was checked for tt at birth. None found. She's always fed well (I volunteer at a bf mum and baby group so nct trained ladies have seen her feed every week) and though small grew steadily. Her weight slowed with weaning but I was assured this is normal and even the graph shows a slowing at that time.
I don't think they grow but i suppose they may become more noticeable as the tongue and mouth get bigger.
I think problematic tt is more about symptoms. So two children could have the same type of tie but one may have symptoms (low weight gain, struggling to feed, painful nipples etc) and the other may be unaffected. It doesn't need to be treated if there are no problems. Get it checked out by all means and keep an eye on speech development etc but you may never need to have it snipped.