I think all Honda would be interested in would be the service history. If it's all with them, then I think you are as qualified as well as anyone re help with abnormal failures outside the 3 years.
I bought mine from a warehouse place, and saved prob £1500 on a Honda supplied similar car. That will more than pay for a reconditioned 'box in the unlikely event I need it.
Mine's a low miler (just 30K at 6 years) but I'm going to change the gearbox oil this spring as a just in case. No evidence of any 'box troubles on mine. If gearboxes are failing, the old boxes will be being rebuilt by specialists and offered as exchange units for a lot less than a Honda new one. Don't let it put you off. All cars have their probs - one thing with a Honda is a) they don't have many, b) they're not the breakdown-at-the-side-of-the-road type (cambelts, fuel pumps, dodgy electrics etc). You'll get a bit of warning.