While sneaky, underhanded, and just plain unethical, it is not entrapment. They are not forcing you to drive fast in the construction zone. If they were truly interested in safety instead of revenue generation, they would have fully uniformed officers working the area in a highly visible fashion as to deter the speeding.

Entrapment is when they tailgate you untill you speed up over the limit, and then light you up to give you your ticket. There are a couple of "officers" in the town of Boyd that will try this at night when they get bored.