fzzzzt, popped alternator breaker C-172M

Ok, here is one for you.

The other night, about the time I landed, I hear a pop and remember seeing a visible flash. I see the amp gauge has a big discharge.

After I taxied off, I try resetting the alt half of the master. The high volt light is dimly lit and glows brighter when I turn off
half the master but that doesn't fix anything. I find that a breaker is popped, so I reset it and everybody is happy again. It is
getting pretty late so I put the machine away.

Any ideas? Everything that was on, kept working. Now I don't know know if it was the field or output breaker but I am guessing by
the flash of light that it was the main.

Pretty hard to trouble shoot a problem that isn't there now, but I am at least going to take a look at the back of the panel with a
mirror for signs of arcing just in case something is loose and bouncing around. (interestingly this happened during one of my better
landings)

Where I was raised, blown breakers aren't something to be ignored.

Mike Z.