Just a comment, but the title ...stolen by U.S. Customs is somewhat prejudicial! In fact US Customs are generally not the ones that are interested in something travelling from Chicago to Montreal, but Canada Customs are!
My point is that the Security screeners may well have seen it in XRays but US Customs don't normally check outbound stuff.
As far as I know, there are also scanners in the handling areas for inbound so the theft could have occurred elsewhere.
I have found no hassles in taking a TT in carry-on. It's not really any worse than a PDA or cell phone. Because many have bluetooth many airline staff don't like them turned on during the flight, even at cruise, though (unless BT enabled) there is no transmitter in them.