British Isles map problem (or not?)

I'm playing the British Isles map & am having problems with my Sentery Planes.
I scouted Ireland with a couple of them & lost my stealth by getting too close to an enemy. I got away & flew to my closest city to refresh my stealth, but it didn't work. No stealth. All the units are of British origin, not the normal AW units. Is it a once-only stealth with these Brit Sentrery planes or is this a glitch?

Must be a glitch, it had to stay in the city for one turn though, you can't just move it through one in one turn.

Even in my new turns (2 so far) it has ended in a city & started the next turn without stealth. I'm just going to put them in a dense part of enemy territory to scout once, then die