Sounds like you had a lucky escape. Glad the tractor driver was ok, that was scary.. I suspect your dad was just worried about your sister having a lot of accidents. You were lucky with the tractor driver, they are notorious for pulling out and two friends were seriously hurt about ten miles away when a tractor pulled out and they hit it.
I remember as a teenager I had a very near miss with a tractor when I was walking along a grass verge and this tractor came up behind me with these big blades sticking out either side over hanging the grass verge. I managed to crawl into the hedge scratching myself to escape them and for the life of me to this day I wonder if the tractor driver was qualified to be driving the tractor.