Thanks Chaos, that pic you posted two posts up just explained my error!!! When I followed the manual's instructions and had the curve part of the tool facing the direction of travel, the dipstick wasn't going in the full depth. I subsequently overfilled (by a hockeysock full) and promptly vented all over my exhaust riding in to work today.
On the upside, my smoke cleared all the mosquitoes in the province!
Draining and refilling properly tonight. :swear: