This is not uncommon. A friend of mine was interested in a nice house with 36 acres farm land. Agent provided a 8x11 copy of the survey map, but would not provide the full survey map. My friend made an offer, but the agent still refused to deliver a copy of the survey. This is a 36 acres of land, with all the easements etc. And the survey does not even cost much. So he was not very happy and the house still in the market. He still does not understand why.
Anyway, ask your own realtor to see if he/she can contact the survey company and get a copy.