What do you mean by "fermented"? Fermentation and oxidation are often confused in reference to tea. Most teas that you will see people discussing here are oxidized by actually physically bruising the leaves, or possibly in some cases via a chemical process, and most of them are not fermented in the sense you're talking about.
I had never heard of Aspergillus mold until your post, but perhaps this (from a quick web search) will clear some things up:http://aspergillusblog.blogspot.com/200 ... e-tea.html
So I think you may be wrong that "most tea" contains this kind of mold.
It appears as if this may be one of the molds involved in the fermentation of pu'er (at least ripe pu'er), and perhaps in some other kinds of Chinese black / dark tea (hei cha). This is different from the type of black tea (what the Chinese call hong cha / red tea) that this sub-forum is for. That kind of black tea is fully oxidized, but not fermented.