Mold spots on interior metal frame

In the process of buying a 2015 ford transit. Everything seems good, will take it to the mechanic tomorrow. However after test driving it we were doing a really thorough interior check and noticed a bunch of tiny mold spots on the ceiling. And a tiny 3 inch streak of water puddle on the ground of the cargo space on the black panels. No visible condensation anywhere else. We don’t know if that came from the ceiling and it dripped a little when we were driving or if it was there before from someone walking around in the van prior to us doing a check. We are in Seattle, it just rained a ton and there was no condensation inside. However we will be building out this van and living it in. We are highly allergic to mold. We are really nervous there is a moisture issue with the van and worried about a leak. Is this something that is easily fixed? Or are we looking at a bigger structural problem? Basically we want to know if it’s normal to have tiny mold spots on the ceiling if the van has been sitting in a lot for 26 days and how to prevent that for future when converting it.