You are the contractor.
Mold can form when the humidity is 55% or more.
The spot you describe just might be where your
shower curtain rests?
Is it on the side where the faucets are? Likely a leak nearby.

Air conditioned air is generally a lot lower humidity, you
have a situation, hidden, that is providing a localized condition
of high humidity.

On Oct 17, 9:23*am, wrote:
My wife discovered a mushroom in the bathroom yesterday.

We have a two-story colonial in a fairly most part of the country.

The mushroom was growing out of the corner formed by the floor, the
bathtub, and the wall. *It wasn't too big, but it's still worrisome.

Does it necessarily indicate that we have a huge problem on our hands?

Anyone suggest what type of contractor to hire to look into mold/
fungus problems?

TIA