Was there probable cause to stop me?

A friend exits my vehicle and I drive away. He makes a sale of drugs without my knowledge to a confidential informant after I am gone and no longer in sight. After the commission of the crime and the informant is gone, I come back to the scene and officers force me out of my car at gun point. I have no knowledge of what took place. Friend never gets back in my car and I was not there. The officers tell me I am being detained, for what they won't say. Later while being detained, a search of my vehicle turns up drugs in my vehicle, not in plain sight but hidden on the passenger side of my vehicle. I did not know they were there nor have seen them for they were not in plain sight. No traffic infraction occurred nor was I given any tickets. Was their search of my car legal? Is their probable cause present? Remember, I left prior to crime and arrived after the fact, whereas I saw nothing and friend never got back in my car.