Mistakenly Melty Mozarella

So here's a question for my cheesemaking friends:

At my urging, a family member recently made a mozzarella using Ricki Carroll's starter kit.  She and her husband used whole milk, but used a different process for heating than the microwave shortcut (not exactly sure what they did...but they were trying to be "more traditional" about it). 

She served the cheese last night at a dinner party, and after it came to room temperature, it was almost melted.  It had the consistency of the inside of a brie or camembert... It was a gooey blob!

She made the cheese about ten days earlier, and had kept it in the fridge, sealed in plastic wrap.

Upon tasting, it was obvious to me that they didn't add enough salt.  I'm thinking that since salt helps expel moisture from the curds, without enough salt it had too much moisture remaining.  But would that be enough to cause it to melt at room temperature?  What else might cause this cheesy conundrum?