There are two separate questions.
The first is was the original English teacher, right to be suspicious of the situation she found herself in ?
I would say YES. Because there have been many, recent terrorist activities, including in the US.
It is quite reasonable, that the teacher can't necessarily tell the difference, between a real electronically timer activated bomb, and a pile of electronics with a timer/clock, noises and what may have looked like parts of a bomb.
The second question is. After she contacted the first person about it, which seems to be the principal. Then others, including the Police. They may not have handled the situation, correctly ?
Presumably the full story has not come out yet. Any parties that have not performed well, may want to keep the exact details quiet.
tl;dr
Up to the point that the teacher, contacted the principle about it. I am happy that, that was correct (given a typical English teachers, probable lack of experience with real bombs and electronics).
But later, it may have been a mix up or something. People tend to start acting a bit weird, when stories of a possible Islamic terrorist, has a live bomb, inside a school, at the moment. Are being reported.