I was cycling home from work today and going up a hill in gear 4. I thought I might drop a gear but decided to stand up and cycle up the hill instead. When I stood up I heard a crunching noise from the hub and it felt like the hub had dropped into a lower gear. I immediately sat down after this happened and continued my cycle home seated. I hardly ever stand up and cycle but I thought this wouldn't be an issue for the Rohloff. Anybody else experience this/know why this happened? This is the first time I have tried cycling standing up from the seat. I've never experienced this sort of thing from a seated position but I haven't had the hub long enough to be certain that it wouldn't.
Thank you everyone for all the advice, it's been a great help.
Unless you turned the shifter? are you sure the noise was the hub or the chain tensioner?