Just left the house, I pulled in the clutch to downshift to 2nd and the engine stopped, the MIL light came on and stayed on.
The bike re-started and seemed to be running fine but the engine light remained.
I trailered it to Ducati as they suggested.
They connected it up to their gizmo and said it had 'over torqued' once (still cold - at 32deg) and that everything was fine again after running a self-diagnosis.
The bike has been fine since.
They did say though that they would have expected the MIL to have reset again on its own and that it shouldn't have latched on like it did.
Perhaps with the clutch a bit cold the bike did indeed 'hop' and cause the over torque?
IMO I wasn't too fierce with the downshift, it felt like the engine simply stopped when I pulled in the clutch lever.