So, I was mining down and found a mineshaft and dropped in, and put 2 torches down. right around the corner, there was a cave spider spawner, so I went and mined it. keep in mind, before i turned the corner, my torches were the only 2 sources of light. So I get the spawner, come back around the corner, and the whole mineshaft has torches along the way. I figure its just my eyes playing tricks on me and mineshafts automatically generate torches, so I keep going along, up until I notice a cave that connects to the mineshaft. Now, I immediately noticed that this cave had torches already in it. So I investigate, and keep following the torches. and there would be little spots where a cave/tunnel meets up and there be a little bit of natural stone in the way, which I would have no way of placing because I don't have silk touch. This creeped me out alot, and this obviously sounds fake, but does anybody have an idea as to what happened?
In my experience mineshafts do have some torches but they are rare and attached to a block hanging from the ceiling. You didn‘t mention if you were playing in a singleplayer or multiplayer world. If multiplayer I assume that another player lit up the tunnels and cave.