I think it unlikely that it is anything to do with the timing belt/chain tensioner. The technology involved with this area has moved on in leaps and bounds, especially at Honda. As to Marco1979's reply regarding the petrol side having to constantly kick in, well most manufacturers have been employing the stop/go engine feature for quite a few years now, and I don't recall any timing issues there. My last 4 Renaults all stopped the engine at every light/junction/traffic jam and never suffered any ill effects. Also, when the petrol/electric interchange takes place, there is momentum involved which would put less strain on the timing chain/belt side of things too.