Being hidden does not constitute entrapment by most definitions:

Entrapment is a practice in which a law enforcement agent […] induces a person to commit a crime that the person would have otherwise been unlikely or unwilling to commit.

In US law, it is defined as “the conception and planning of an offense by an officer or agent, and the procurement of its commission by one who would not have perpetrated it except for the trickery, persuasion or fraud of the officer or state agent”

Basically, entrapment is getting someone to commit a crime they would not normally commit for the purpose of arresting them.