As I think about it more, I am assuming that they actually did think that I was the one who "called it in". When I yelled "heads up", they may have assumed that it meant, "Hey, heads up! I am the one who called in the body!!"?? I ran into my commuting buddy near the end of my ride and he told me that he saw them, but they didn't stop him to ask if he found a body. When I yelled to them (from far away), I had no idea at the time that they were firefighters (looking for a body).