Horse that lays down...

I have a young 2 1/2 year old quarter horse gelding. He has been trail riding, etc. and is a very nice horse we paid $2,500 for and has a good line behind him. My question is he layed down 3 times under little stress-- once with trainer pushing him for about 5 min., once while getting his front feet tangled in rope while tied, once at his feed dish not tied. We have had him check by vet a couple times they said he needs taught manners. This horse is not agressive and in fact low man on totem pole by far. He does not kick or anything, just a sweethart. I was talking to a girl about this and she came up right away with the horse has no confidence in himself. This is first I heard this even from trainer, vets, etc. Does this make sense? What is your opinion on a horse that lays down (and eats grass, not upset at all) when something doesn't go his way?

Reply from trainer Tracy Zadow:

It sounds like he reacted to a stressful situation. It's not so much the single act of being worked or being tangled. His stressful situation is a new home. I usually give a horse a full week to get to know the routine, sounds, smells, and aquainting themselves with the other horses before I add anything else to his day. A horse that is low on the totem pole can take a little extra time to adjust. He's just one of those horses that does a quirky thing when overwhelmed. He is young and his mind is still maturing so I'm seeing that with maturity he'll be able to deal with stress better.