Police Radar and iPod FM Transmitters?

When I was coming home tonight, I was crossing the Buckman Bridge and something interfered with my iPod's FM transmitter. It was the same kind of interference I get when I get a call on my cell phone. Anyway, I got off the bridge, I saw that the car right behind me was a police car. (The transmitter was on 90.3 FM--if that means anything.)

My guess is that the cop was using the radar gun on me, and that's what was interfering with the iPod. Anyone know if my guess about what was going on is right? Has anyone else observed this phenomenon? I'd wonder if it's reliable enough to serve as a stand-in for a radar detector (one that would be legal in places where radar detectors are illegal). It also make me wonder about the safety of police radar--though I do tend to think most of the fears about cell phones, radar, and related EM emitters strikes me as baseless technophobia.