We claim the ornamental design for a grain inspection device, as shown and described.
FIG. 1 is a left front perspective view of a grain inspection device showing our new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines in the drawings are included for the purpose of illustrating portions of the grain inspection device and form no part of the claimed design.