u/Expensive-Flounder77

I just noticed recently in my downstairs hallway this tiny crack in the paint accompanied by some discoloration. It is about 3/4 of an inch long. What is this? What should I do? There are no active leaks or anything in the house (we bought it in November of 2025). There is an upstairs with a bathroom but again, no active leak. Any advice? Thoughts? Thanks!