I think any shop that orders a bike at a customers request would order the correct size for that customer.

You said no money was exchanged so I would say it is not a sale until you do so. Take a look and test ride when it comes in, if it fits and you like it buy it. If not work with the shop and get the bike you like and fits.
Seems to me the shop is a good one if they are getting in a bike just to see if you like it. It could be though that they know it will sell anyway.
Good luck , hope you like your new Jamis!