Limited knowledge of the MD11 - but I understand that in order to reduce drag (= less fuel) one of the modifications made to the DC10 when it became the MD11 was to reduce the size of the Horizontal Stab (look at the rear of two next to each other and you will notice this quite easily). This does have the effect of reducing the natural stability of an aircraft, and some clever software in the flight control system copes with this to give the pilots the same (v good apparently) flying characteristics of the DC10.
Should you be worried? No.