They are a pain in the arse, tin plates.
I had it happen all the time here in "06" land
before we went to non-departmental numbers.
And they get bent and ripped off by scooterists.
What made you choose them?
Purely aesthetics and an interesting material difference to the ubiquity of acrylic. In researching them I was aware of the potential drop out problem, so I did ensure the adhesive strips bridge those areas. Lets see if it becomes a problem...they were only £20, so not a huge loss if they do.