On Sunday, February 18, 2018 at 9:56:55 PM UTC-6, John Doe wrote:
I have no idea, that's why I am asking.

I just drilled into some wood, a baseboard. The area is
nowhere near anything that could leak, it is a closet in a
corner of the upstairs house. After drilling, the wood in the
bit seemed wet. So I thought, maybe rain. But it smells like
turpentine, or something very similar.

An old house, but the addition is not that old (I think). I
really have no idea what it could could be.

For a few months, there was a canister of propane sitting in
that corner. But I am careful and doubt that it leaked
anything. Not that it would smell like turpentine anyway.

There isn't anything over there... And turpentine is volatile
so it would not stick around for years?

If somebody left a can of turpentine in the wall, certainly
it would smell? Seems weird to me.

Thanks.

As Whit3rd said, it could well be that you drilled into a sap pocket. If you drilled in an area that does not show too much. Drill a couple of other holes either side of the one you are talking about and see how large an are you are dealing with. Also, as Whit indicated, if the drill has any sticky residue, that is an almost certain indicator you are dealing with said sap pocket.