A red triangle indicates that traffic is rising so I would have to assume each hub would only have a maximum of 1 red triangle at any given time. It wouldn't make sense for there to be multiple red triangles on 1 hub. Maybe I'm wrong and some people see multiple red triangles when traffic sky-rockets. I have never seen more than one on a single hub though.
EDIT: Indeed I am wrong! LOL...I am jealous of those who get more than 1 red triangle now!