Is there more to this than meets the eye?

[Eric from Newton]

Hi everyone, I appreciate your taking a look at my situation. I have a cast iron stack in my basement that has a couple of old (I think) stains on the outside of the pipe. Nothing that appears to be an active leak, but still a bit unsightly and a little worrisome. This house was built in 1899.I've taken some pictures and I'm wondering whether anyone has seen these kinds of leaks before, and whether they are a problem that needs to be addressed right now, maybe later, or not anytime soon.

Thanks much!

 

[Plumber69]

looks like a vertical run. Leave it alone

 

[Sponsor]

 

[Eric from Newton]

looks like a vertical run. Leave it alone

Yes, you are correct, these pipes for the most part are vertical.