It’s just a little mold, right? You can clean it, and it stays gone for a while, right? That means it’s not a problem, right?
Here’s such a situation. There’s just a little mold in the corners. It stays clean for a couple weeks after scrubbing, but it always comes back. The shower has already been repaired once, so it should be fine, right?
Here’s what it looks like from underneath. The repair doesn’t appear to have worked. The subfloor is damp to the touch, as well as being spongy. The rot hasn’t just started, it’s progressed to the point where the subfloor will have to be replaced before the shower (and it’s occupant) falls through into the basement.
Call in the pros, The Shower Pros!