Defensive calls Illegal...?

[jjrye22]

I actually had a disconcerting signals in a game this year. I was FJ and back about 18 yards, and even I clearly heard it. The O jumped offside at the signal (a hut from the NT) and flags went (not mine).
I ran in to ask the others if they had heard the hut from the NT and they all agreed that he had done it to draw the FS.
No real problem and no discussion - most teams around here are quiet on defense which would make it obvious if they try something like this.