This automatic wiper start caught me out as well. Possibly made worse by snow/frost over the rain sensor.
I also found that although I had cleared the ice and snow off the rubber blades themselves the wiping performance was rubbish ,with large areas not wiped at all. I thought I had shredded the rubber.
Fortunately once I stopped again and took the trouble to also remove every bit of ice from the BACK of the wiper blade (ie the broad flexible backing) this restored full flexibility so the blades again fully conformed to the curvature of the screen.
My first trip in foul and variable weather made me realise I didnt know the multiple functions of the wiper and lighting stalks nearly as well as I thought I did. I had muddled through, finding wipers by trial and error whilst driving, which sufficed for the occasional bit of rain, in daylight. I really need to study the manual again until I can instantly deploy the full range of wipes, and fancy lighting tricks without conscious thought.