[Aerkuld]

I have a Passport 8500 X50 detector in my car, which I must say has saved me from embarassment on several occasions but today I had something happen that has never happened before - It gave me a warning for 'LASER'. I was driving the 944 and doing the speed limit so no problem there. I was just suprised. I am familiar with all the other audible alarm signals it gives but have never heard this one before while driving. It came on for about 2 seconds, went off, then came on again 5 seconds later for about the same period of time. I didn't see partol cars or cops at the side of the road even after driving another half a mile or so down the road, so I was wondering if anything else is likely to set it off?
I was driving past the local airport at the time - are they likely to have anything that could trigger it? Funny thing is it didn't trigger it driving the same route in the opposite direction.