Herd bound, how quick do horses bond?

Question
Hi, last week I bought a 16 year old gelding to use as a trail horse. This is my first horse, but my husband has two that he keeps at his family's farm.  My in-laws agreed to let me keep my horse there as well.  At his previous home, he was kept in a small pasture with one other horse.  When we brought him home, we put him in a corral alone.  The following day, I rode him without any problems and put him back in the corral alone.  The next day I rode him without problems, then let him in the pasture with two other horses.  I came back the following day and had no problem getting him from the field or putting on the saddle, but he threw a fit when I tried to put the bit and bridle on him.  He did accept it, but I could tell that he was tense when I was able to ride him, as he was constantly trying to turn around.  (I didn't let him).  Today, he came out of the pasture fine and saddled fine, yet it took me an hour to get a bit in his mouth.  He was pacing in the corral, and whinnying to the other horses.  (They actually weren't paying much attention.)  I walked him away from the barn and pasture before getting on him, and then rode away from the barn.  But like yesterday, he kept trying to turn around, whinnying, and just wasn't happy.  

Could he be herd bound after just a couple of days in the pasture with two horses he has never met?  His previous owner did say that he was herd bound with her other horse, but once they were out of sight of each other, he was fine.  With me, even though he was out of sight of the other horses, who didn't even seem to care, he was still agitated.  I don't want to keep him in the corral all the time...would putting my horse in a pasture next to the other horses help all that much?  Thanks for any help you can give!

Answer
Hi Michele,
             There are a few issues that your horse could be having. If you do not know the person that you bought the horse from, then there is always the chance that he may have been medicated when you saw him which would account for his change in attitude. He also could be home sick for his old home and the horse that he was pastured with. I would put him with the other horses as they are herd animals. I would also once in a while switch him to the other pasture. Right now I would also spend the next week or so grooming him and letting him get to know you. Horses are alot like people and need time to adjust.

Good luck with your new horse.

Lisa