Your post and comments screamed “Indian” lol.
If you’re a man, it’s better you don’t mention it at all. We can mostly sense it when the strap is out. If we haven’t adjusted it, it’s simply coz we are not bothered, so you shouldn’t be bothered either. If you’re a woman you can simply signal them that it’s showing, no need to make a big deal by telling them out loud or pulling them aside. Indian aunties go a step further and adjust it for you, it’s so infuriating!
PS: I’m Indian too.