Not odd to have Dispatch on speed dial. Every stop should generate a call to Dispatch. That's usually a radio call, but once that call is made, ID is verified, license, registration, insurance etc checked, AND any outstanding warrants checked, by that time, sometimes it may be easier for the officer to answer additional questions without tying up the radio freq. In that case, it's a phone call, usually on some speed dial set up.
If bird poop can show a positive, the what else can show a false positive? Maybe the bird was partying in an upscale neighborhood, and really did pick up some cocaine, "somewhere?"