I do recall it happening twice a few years back.
“A large canine taken by a coyote hunter early in January east of Hillsboro, N.D., in Traill County has been confirmed as a gray wolf. The hunter apparently shot the gray wolf, a protected species rarely seen in North Dakota, thinking it was a coyote. According to Gary Rankin, district game warden for the state Game and Fish Department in Larimore, N.D., the hunter called him after realizing the animal probably was too big to be a coyote. Rankin then picked up the animal.”
And also the one shot and left wounded near Edinburg:
“The day after dispatching the wolf, Freeman said he received a call from a man who said he'd shot the animal, thinking it was a coyote. Gray wolves are federally protected under the Endangered Species Act, but the U.S. Fish and Wildlife Service isn't pressing charges, Freeman said.” That guy may have faced state charges though.