Sassenach said:
This is so out of the ordinary that I urge you to check out the bona fides of this publisher asap.
Major red-flaggage.
Unusual, yes; unheard of, no.
Usually happens when visiting editors nose through MFA programs (Iowa, UC Irvine) and are struck by a WIP. I've also heard of it happening at conferences where editors do advance reads. Keep in mind
interest in a ms. is a long ways from a sale.
But Sassenach and Maddog raise an interesting point, if you don't mind our prying: How did you happen to come in contact with this publisher? (You weren't sending out an unfinished ms. over the transom, were you?)
In any case, have you checked this publisher in the threads at this site (look under the INDEX TO AGENTS, PUBLISHERS AND OTHERS at the top of this forum)? That's where I'd start...