A parallel thing happened to me the other day. My grinder is to the left of my lathe, turned 90 degrees to the lathe. I use a magnet - to collect the steel shavings - located just below the wheels, attached to the Wolverine jig.
So, I had air-hosed the shop, did a good clean up, and did not realize that any of the dust had settled down in the metal shavings attached to the magnet. I had not considered that these shavings bore a similar appearance to steel wool. I sharpened a tool - then noticed that the magnet loaded with steel shavings took on a glow...not on the surface - but - down in the shavings. .I grabbed it with a pair of channel locks, and took it out in the grass, And let it burn out.
It was an ..."enlightening experience"