I believe most drivers are aware when someone is following them, even for a short distance of time... atleast I'm aware. The likely hood of someone following you from your bosses house is there, but I doubt that's the case. Could've just been some l33t nerd that wanted a new computer.

Since your alarm went off, that would definitely cause a theif to think quick and act quick; take what you can get. They're not going to sit in your car with the alarm sounding, trying to take your headunit when a very nice computer is sitting in the back seat, IMO.