Yup- moisture got in and condensation caused the droplets which are now damage. Damage like this is very common and not always related to someone swimming or showering with the watch.
When the rear seal and crown seal (and pushers too if it’s a chronograph) start to age they lose their ability to keep the moisture out- it can be sweat from the skin or even ambient humidity. Go from a hot humid day outside into air conditioning and it can happen if the seals are compromised. I don’t wear watches with vintage crowns or aren’t waterproof in the heat of swampy summer.
For those who just have to have that original crown and throw caution to the wind regarding the rock hard/goo like gasket inside- this is your future.