Wasn't on Route 9 but had something similar happen on the A556 a few years back. Pulled into the drive and my wife said I was two hours late, I genuinely had no memory of anything past a certain roundabout. Felt completely fine, no grogginess or anything, just a clean gap.
The thing that got me was the mileage on the car didn't add up either. More miles than the journey should've been, which still bothers me tbh.
Did you notice anything before the gap - weird lights, feeling suddenly calm or drowsy, radio cutting out? Those seem to come up a lot in these accounts. Would be good to hear more detail from others who were on that stretch last Thursday because if there's multiple witnesses thats a completely different conversation.