Strange Rosy boa behavior

For the first time in 2 years my rosy boa did not eat. I feed him every 10 days. I feed f/t mice the same size as the widest part of his body. Is this just one of those things that happens occasionally or should I assume there is an issue since this is the first time in slightly more than 2 years of having him that he didn't feed? Thanks for any and all suggestions. I know this may not be a huge deal but I want to make sure I'm not under or over doing anything. Thanks again.