[Vocabulary] What is the meaning of "tip-off" in this situation?

[mokbon]

Hello

This is situation
---------------------------------------------
Chuck: Are you following us or something?
Dan: No, I go to your school. Identical uniforms, isn't that kind of a tip-off?
Nate: That's funny.
---------------------------------------------
(From Gossip Girl)

Can "school uniform" be "a tip-off"?

 

[nyota]

........................
I'm not a teacher
........................

I believe Dan's saying the fact he's wearing the same uniform should give them sort of a hint he's going to the same school.


tip-off (AmE informal)

Something that shows you that something is true, even though you did not expect it to be true e.g. - The fact that he hasn't called should be a tip-off that he's not interested. Longman