92 Civic EX with a Melted Distributor

Hi, my 92 Civic EX, with 168k miles, quit on the highway the other day after
an hour of driving. I just had the chance to investigate and decided to
start looking with the last bit of maintenance on the car. About 2 months
ago I had an igniter go and replaced that along with the coil (I know not
really necessary), plug wires, plugs, rotor & cap. When I got the cap off,
I noticed that the rotor appeared melted into the dust cap as if maybe one
of the components wasn't the correct one for the car. The cap itself had
pieces of rotor inside as well as contact between the rotor and the arc
studs for each cylinder. I suppose it will be easy to call to determine if I
have the correct part numbers. I'm just curious has anyone ever heard of
this occurring? Is this usually how distributors fail? There must be a
bearing or two inside the housing, could possibly one or both seized up?

Mike
Somersworth, NH