Collected the bike this afternoon and have had a good 30 mile ride with varied traffic conditions and speeds etc and all seems to be fine.
So, they put it on the diagnostic machine and it showed an issue with the rear abs sensor, reset - road test- abs light comes on again. went through the same routine again and the same thing happened.
Technician removed rear sensor, thorough clean and brushed up the rotor on the rear wheel, reassemble - road test and all clear.
Whilst they've not experienced this particular problem with the DL4/5, they have had similar issue occasionally on other bikes.
So it seems the rear sensor, which is linked to both abs and TC can cause all sorts of hiccups.
Moral is to clean it frequently. Hmmm, me thinks................ this is an adventure bike and is likely to get filthy from time to time.
Anyway , we'll see how she goes.