Technically once they found out your license is suspended they can do an inventory search of the car for the purpose of towing it. You are technically under arrest but in most cases they just issue you a notice to appear (citation) even though driving on a suspended license is a Misdemeanor so you too are subject to search. Looks like the cops were being cool and cut you some slack jack. They probably were looking for the big fish and just threw you little guppie back in the sea. So like the previous post said, be thankful they didnt tow your shiznit and let you go on your merry way.