An annoying bug (well, I consider it one) is that if you have a season
ticket on Oyster, PLUS some pre-pay (for paying out-of-zone extensions automatically), then the
gate does NOT tell you when your season is due to expire.

However, if you JUST have the season, then it does tell you "Tkt 1 Nr Expiry" (or similar).

The prepay doesn't affect if the "ticket soon expires" message appears, its
the type of gate you are going through. Old gates only show it when you
exit the system and you have to look to the side on the LCD screen.