This happened to me ALL DAY. There was nothing on my shirt, it was on straight, it was full coverage - no boob action, no crumbs, no random animals or bugs clinging to my shirt, NOTHING.
So WHAT was everybody looking at? I even went to the bathroom to check, and asked not one, but TWO people if there was anything on me, and I got the same response every time.
"Nope, nothing there."
Was the pattern on my shirt so mesmerizing that these people felt the need to glance down at least fifteen times during our conversation(s)? Was the baby in my belly doing that weird alien thing and pushing outwards on my skin when I wasn't looking, and I somehow didn't feel or notice it at all?
And here's another thing: if someone has something on their shirt, or their underwear is hanging out, or their pants are on backwards, or a forest is sticking out from their teeth - TELL THEM! It's NOT rude to give someone a heads up about this stuff; it IS rude to STARE at the offending item on their person NONSTOP and NOT say anything thus CONDEMNING that person to walk around like a DOOFY asshole all day.