that's a new one for me. Most the stuff I hear is:
100s - day patrol
200s - swing patrol
300s - grave patrol
Victor - Sgts
I would guess it's one of the commanders, what time did you hear it?
Also, if your scanner cut off the first part of the designator it could have easily been Littleton PD on their channel. The last part of their patrol designators a go up to 6 (i.e 3A1, 3A2, ...3A6). There is almost always an "A" in the middle).