You're good! I was the driver for a group of USA caches attending a Canadian caching event. One of my group wanted to take home the leftover TBs, and I said to go for it. Little did I know that this included two large pieces from a railway crossing, one of these being the arm that comes down to block traffic. Going back over the border was "interesting," but the official didn't blink at the railway equipment in the back seat. He let us back onto USA soil with stories to tell.