It could be imho the rust stains on that bearing in the right of the photo looks like moisture has been there quite a while.
More experienced members here will have seen worse - probably just normal on an old bike like ours even more so if not used over the winter with no oil splashing about.
Not forgetting that water emulsifies with mineral oil - less so with sythetic oil that we can't use as they put micronised chalk into modern oils to stop acid formation from burnt sulpher.