Are these eggs rotten?
What you're describing sounds normal to me. It's the result of overcooking them. The eggs themselves were fine. At a guess, you unknowingly messed up the timing for the particular batch described here (alternatively, the eggs may have been smaller than usual). 

Over cooking hard boiled eggs will result in the smell you identified (and also cause the exterior of the yolk to turn green). 

Further information: http://io9.com/when-you-overcook-eggs-you-turn-them-into-chemical-wea-1682497376