Recently changed my plugs and wires

The coil had corrosion like you would see on a battery terminal

...coil picture...

...coil wire picture...

Plugs and wires have 13,000 miles

It's a pertronix flame thrower coil.

Just curious it this is common or indicating a problem with the ignition system.

I did leave the ignition on a few months ago for about an hour by mistake.

I changed the coil to be on the safe side.
Thanks