Buried at home in a drawer is a souvenir t-shirt from the London Underground, which admonishes one to "Mind the Gap." Recently I was hit by a wave of nostalgia after seeing the same reminder on a King County Metro bus.

The phrase began as a friendly reminder for Londoners riding the subway - the tube - to be aware of the space between the passenger platform and the car they were boarding. The warning is everywhere - on the walls and stenciled on the floor.

I noticed the words in white letters on red on the doors of a Metro bus as they opened at a station in Seattle's bus tunnel. Turns out it was a curious fluke. A Metro spokesperson told me the sign was a remnant from the tunnel's reopening in 2007. It was closed for two years for rail installation. The concern was how returning bus drivers and riders might adjust to, well, the gap. So a clever idea was borrowed.

As it turned out, it was no big deal at all, for transit personnel or passengers. And, apparently, there was some confusion. The advisory did not translate well for some folks. The idea was dropped in the dustbin.

Mind the Gap appeared in London's tube in 1969, and the phrase or variation on the theme has spread around the world. Seattle apparently did not need the reminder. I saw a wee bit of local transit history, and found some inspiration to track down a souvenir.