The article is misleading. I've never read anything about them seeing a holster which prompted a search. I doubt that a search prompted by the sighting of an empty holster would even be legal. Instead, they were searching for more drugs after they found some on the guy (also a Browns player but who was subsequently cut) sitting in the passenger seat.
All in all, the quoted comments of the police were that Warren was polite and cooperative.
This will hopefully be the last time he accepts a party invitation from a Steelers player (Plaxico Burris). Pittsburgh is not the friendliest place for a Browns player to hang out.