I'm sure you'll be fine horsey! It's funny what makes us all worry - I'd be terrified of getting injured falling off a horse if the horse freaked out at something - but probably wouldn't think twice if a dog jumped up at my bump (possibly because they'd likely hit junior in the arse given their current position).
I remember when my sister was seven months pregnant and still cycling 12 miles a day - we were all terrified for her wee one as there's not much to protect them if you come off the bike so late in pregnancy. She was very blase. But now she thinks the worst of most situations and is a real worrier. My irrational worries are far too many to list... but include DH driving too 'rally driverish' up our rough country track... errr, bending over too quickly and trapping their neck in my pelvis (not possible is it?) and numerous other hormone fuelled craziness...
Come to think of it horsey a dog bounce is a much more sensible thing to worry about than what I worry about
. But I am sure Junior is fine. How are you feeling after losing your mucus plug - do you think you lost it all? Do you feel as though you might be progressing toward labour?