These things typically do not occur out of no reason. If there was 'no reason', you should experience symptoms randomly. When given specific, identifiable, and controllable set of stimulus, you predictably experience the same symptoms. In some cultures, the presence of authority produces joy. In others, fear. Some other cultures might feel rage in presence of authority.

Hey, It's not the most important thing in the World but it would be nice to figure it out and if possible, to address the actual issue.

Figuring out other times in your life either in the present or in the past that makes/made you feel tense or nervous might be your way in to figure out the origins of this quirky issue.
Most of believe what we are.