Getting out of the saddle was my downfall today. Unless i went over some black ice which is a possibility i think i just lost balance standing to climb and the bike just seemed to go. Cue a very dirty new bike, me laying on the wet floor half way up a 6% hill. It took me ages to get my right foot out.
Never mind, it can happen

Hope the bike's ok

I also fell when i got home in my driveway, steep learning curve!