The AP who is doing this has an agenda and that agenda is "gotcha". Too bad the gotcha hasn't worked very often because the teachers do what they are supposed to do, TEACH until the very last bell of the day rings.
I never understood this gotcha mentality. Happy teachers are better teachers. Why would an AP who cares about his charges do this Why would a Principal who wants to run a good school condone such actions? Is this because the AP and the Principal care more about making the life of the teacher uncomfortable than they care about the welfare of the students they are in charge of?