Having the ability to get a lot of different yoyos come through my hands I can say it may have been a little corroded. I see it more frequently than one may think. A little finger sweat on a steel axle is all it takes. If the axle is a little worn and has been left in the threads for a bit to corrode it can come out looking like that.
What did the threaded end look like?
I only use stainless axles when replacing. Yes stainless can gall but usually when used in stainless to stainless applications. Even the axles that have the black oxide coating are prone to corrosion. A few times in and out and your on your way to bare steel.