They call it "acceleration." It's applicable as a "remedy" for certain acts the lender doesn't like. My latest was with GMAC, FWIW.
For example, his friend may not have, by law, owned the houses, but may have transfered rights to his business. If the lender somehow knew this and didn't like it (not a "natural person), it may have triggered an "acceleration."
Don't know his contract details, just a possible scenario.
Really? Where and what originating financial institution?
I read my notes and I don't remember anything like that. (I found a lot of other things that I wasn't happy about.)