@sanji No, definitely not an isolated case. I lost mine about a month ago, and luckily I had a spare one that arrived packed together with Easy Wheels (I don't know what #Brompton packs this together...). And just the previous week my friend also lost it, realizing it by the sound of the tube hitting ground.
I have put some isolating tape around mine now (around the part that goes in the tube) while my friend temporarily improvised by using holiday remainings (photo).