Fiona, personally I haven't experienced this, but listen to your OB. I'm sure if he was worried he would have organised another scan straight away not wait another week. I know it's easier to just tell someone not to worry than to do it, but try to just enjoy your pregnancy and have your scan next week. Maybe feeling the first movements on your way home is your little one's way of saying everythings ok.
Sending you hugs and good thoughts for your next scan.