Is the rent still owed?

[Arialena]

My husband and I lived in the same apartment for several years. Last summer we moved out of the apartment at the end of our lease because we bought a house of our own. Just this month, the landlord deposited our final rent check (almost a year old). The bank has reversed the check because it was stale dated. My question is whether he can still attempt to collect that last month's rent. We mailed the check to him on time and he says that he lost it and only recently found it. He claims to have tried to contact us although in the entire last month of our residency and the month that followed (while we tried to get our security deposit back) he never once mentioned the lost check. Do we have an obligation to pay him that one month's rent? Thanks.