I don't know about DC-10, but many years ago when annual "C of A" test flights required verification of stall, etc, we had a DC-9 that frightened everybody by stalling about 10 kts sooner than expected.
When being investigated, it had flown through a cloud of insects and what we thought was minor leading edge contamination was enough to cause a significant stall speed deviation.
Similarly, a brief passage through an almost invisible layer of stratus (as in climb-out) can put a thin layer of ice on L.E. that is not noticeable in a casual inspection. As the climb continues closer to the limiting altitude, it is silently sitting there waiting for the unwary.
Supercritical wings are efficient, but touchy.
edited for spelling