the car lost power, clutch and accelerator lowered and I pulled in?

Long question here. Last November I was on a 3-hour journey. About 2 hours 15 minutes in, the car lost power, clutch and accelerator lowered and I pulled in. Turned engine off and went to start car but all pedals were in raised position as normal but were completely frozen/stuck. I thought the car was gone but after sitting for 30 minutes, the pedals unstuck, and I was able to continue the journey. Next day, drove all day fine. Day after, the same until i was an hour from home and same thing happened again. Now, this hasn't happened since then. 7 month and nothing, although my journeys haven't been more than 2 hours since. Any ideas? My mechanic said he has never come across that. I asked maybe clutch/flywheel, but he drove it again yesterday and said apart from small clunking sound, flywheel still has a Good few months in her. He said it wouldn't be a flywheel issue and said clutch etc., feels fine. Sorry about long post but those two times back in November are really odd