US customs Delayed Baggage Rerouted

Something odd has happened with my delayed luggage and I’m hoping someone here has heard of this situation before and can comment.

I was originally scheduled to fly BOS-PHL-LHR but the flight from PHL-LHR was cancelled and due to the nature of my trip, rather than continue on the following evening and miss the event I was originally traveling overseas for, I decided instead cancel the trip and return home.

When I landed back in BOS the next afternoon, my luggage had not traveled with me. In fact, it had for some reason been sent to YYZ where, according to the baggage representative in BOS, it would be located and sent back to BOS. Not sure how my luggage ended up in YYZ in the first place but here’s where it gets weird. I call the delayed baggage inquiry line after 24 hours as the airline online system is still showing only my bag as having arrived in YYZ. The baggage agent tells me that US customs will not allow my bag to fly, and instead they will be driving it across the border to BUF where it will then be sent via plane back to BOS.

Has anyone ever heard of this before...US customs not allowing a bag to fly but allowing it to drive over the border? Or is this just the airline trying to make it take a couple extra days to get my bag back as a nice little cherry on top of the ruined vacation sundae. Any insight would be welcome. I will say I don’t have any batteries or e-cigarettes or any of that stuff in my luggage. Just a dress for my new niece and my fly fishing gear. Thanks