Or if rodents get in an chew on the belts...I think there have been a few posts regarding that in the last 3-6 months.
That area should've been sealed up, how did a rodent get in there? Unless someone replaced it and forgot to put everything back. This site is adamant about replacing the belt every 90K miles, i'd go 200K miles before replacing mine if it was factory. If someone replaced it, i'd go back in there and double check their work and make sure right parts were used and everything is torqued up to spec.