WARNING MESSAGE: GARAGE

[Brunel]

Key/fob inserted as usual, all lights appeared as normal, usual sounds, fob fully home, engine turned but very slow, warning message appeared in panel

Engine....... GARAGE.

Removed fob, waited 10 secs, re inserted, engine turned over full speed and started.

Has been perfect all day.

Could it be a strange battery fault? still the original, 9 yrs old, checks ok, of course it cannot be as good as new one.

Thanks.