Acid free > mold?

For years I've been printing on 100% archival materials. Last year I had to move at a moment's notice, and everything, including my prints, went into storage, which was not climate controlled. My older prints were fine, but my newer (archival) priints were about 50% mildewed/molded.

 

Is it because they're acid-free? Would the acid have provided protected against mold spores?

I am not trained for achiving, but it is not likely because acid free paper. After relative humidity goes over 75% and if there is environment temperature changes, moisture will appear. Inkjet inks have some sort of oilyish solution, which might be glycerin, fresh prints are perfect base to cultivate fingerprint and aerial bacteria contamination in moist environment. If there is acidity in paper, it would reduce risk of mold, but would weaken archivability otherwise.