The ornamental design for a surface mount warninglight, as shown and as described.
FIG. 1 is a front perspective view of a surface mount warning light showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a back view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a left side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines included illustrate portions of the surface mount warning light that form no part of the claimed design. The cutaway symbols illustrated in broken lines in the drawings indicate a symbolic break in the length of the design for the surface mount warning light indicating an indeterminate length.