Here's a thought, taken from one of the EMS magazines...
If your "spider sense" is saying something dosen't feel right.... it isn't right. Often you will have a feeling of unease over something that you saw 'subconciously' that you don't even realize you saw (like a gun, or how someone was moving).... that is where the "spider sense" comes in...... you don't know why, but you get the feeling that something is wrong.
When your "spider sense" tells you something is wrong, belive it. Make your partner aware that you have a "bad feeling" as well... 2 sets of eyes are better than 1. Try to remove yourself from the situation as well... get the patient into your rig, and out of the house / mall / corner store.
However, just because your "spider sense" isn't in alert, dosen't mean that there isn't a problem...
Jon