I have a VERY strong preference that players not roll for Insight or Perception unless one of the following situations applies:

a. You're in combat and want to spend a Minor action to try to get a better result than you think you're getting from your passive;
b. I explicitly ask for a roll;
c. We're in a skill challenge and you want to actively apply the skill.

In my opinion, Passive Insight and Perception make roleplay flow a lot better by allowing your investment in the appropriate skill (or lack thereof) to impact the flow of roleplay without dice rolls. Unsolicited dice rolls disrupt the flow of the dialogue.

When in doubt--DON'T ROLL.