I was kind of bummed the other thread was locked, because this is an interesting and problematic issue. I found it funny when you said you were excited to have the K9 come out to sniff the vehicle, because I would have thought the same thing.
But I always wondered how bringing out the K9 without a warrant is constitutional. I can sort of understand it at the border or airport, but at a random traffic stop? It doesn't seem right. Especially when you can make your dog false alert. I heard a story on NPR some time ago about an ex-cop who admitted that he did this.