"A person told you that they were not doing anything illegal and that caused you to have a reasonable suspicion that they were doing something illegal? Does that make sense to you?"
As an honest law abiding citizen, I do see your point, however you must have never been LE. As a police officer, I have rarely had any criminal ever say they were guilty and were doing something illegal. Almost everyone says they are "not doing anything illegal"
Good luck, and be safe.