Raw Sesame Oil off-gassing and turning stuff blue?

Hello! A few months back, I sanded down an old lifeless and grey Stanley awl handle (more or less bare, if I recall) and did an experiment to refinish it. Notably, I soaked it in a cup of sesame oil for around a week. I figured I had nothing to loose, and it might give back some life and moisture to the wood. I know very little about finishing, but it made sense to me.

The awl had been untouched in a toolbox in my parents basement for maybe 35 years, and as such, it smelled like a basement, and maybe a little like gasoline.

Anyway, after soaking the handle in raw sesame oil for a week, I took it out and dried it, and set it down on a paper towel so it had somewhere to leak. The wood had gotten a lot darker since soaking it.

But something strange happened. Dark blue marks were showing up on the paper towel. I wrote it off, and let it dry out a little more. By the time I thought it had dried out enough, a pretty bold dark blue mark was on the paper towel. Much darker than before.

So I threw the awl in my toolbox, right next to another wood handle. I opened the drawer a week later, and the other tool's handle had a dark blue mark on it! Then a week later I checked again, and it had spread a little.

My question is, what's happening here? It reminds me like an extreme form of ammonia gassing, but I can't imagine raw foodgrade sesame oil has anything capable of that, in it. But something is at work here, clearly. I can post a picture later, if you like.

So, is it a reaction between the oil and something that was already in the wood?

Is it simply the sesame oil doing its thing?

Has anyone had anything like this happen before? It's pretty interesting. I'd love to hear theories about it, or an explanation.

Thanks for reading!