Advice: Is this normal?

[urban_twilight]

So I've been trying to sell my horse for almost a year now and only recently have I gotten some interest. I'm having some people coming up to see him this Wednesday and I learned that they are bringing their trailer with the intention to bring him back with them if they decide that they like him. Now, I want to know if this is a routine procedure when selling a horse. I've talked with these people once or twice and exchanged several emails. I know where he'd be going and a little bit about the people but I'm hesitant to just have them come meet him for a few hours and then just take him away. He is my first horse and the decision to sell him was one more of necessity than anything else. He is still my baby and it's going to be very difficult for me to let him go when the time comes.  I haven't experienced this sort of situation with any other potential buyers; they usually want to just come see and ride him before even considering making an offer, let alone going so far as to bring a trailer along with them.

Now, I'm trying to figure out a way to express my unease without being discouraging. I do feel very positive about these people and would be very happy if it worked out. However, I just don't feel comfortable with that kind of scenario. Am I overreacting? Is this something commonly done when selling a horse? I just don't want to seem like I'm backing out when I would still very much like them to come see him. I just don't think that kind of decision can be made with one visit. Not to mention smoothing out other legal issues like the actual sale of the horse. And wouldn't they want to get him checked out by a vet or at least confirm that he has all of his vaccines etc.? Basically I need to know if I should be worried about these people or not.

Thanks!