Right?
My brother was sneezing and sneezing and left the room. And then when he was readying himself in the bathroom down the hall, (with the door open, mind you, so we are capable of holding conversation if wanted) he sneezes and I don't say anything because I don't know, it didn't seem 'appropriate'. And then I think, 'Well, obviously he knows I can hear him.' And feel guitly for not saying it, and by the time I want to say it, it's too long of a wait to say it without looking weird.
That's when I remember how annoying this habit is. I ALWAYS do that too.