David leased an apartment from Double H from July 1995 to July 1996 for $1,473 per month. After that, he continued to live in the apartment on a month-to-month basis. In 2003, Double H notified David his rent would be $1,488 if he signed a new lease for a year, but otherwise the rent would be $1,561 on a month-to-month tenancy. David started paying $1,488 but he did not sign a new lease. He alleged the manager agreed to this after David negotiated with him. Double H sent David a past due notice for failing to pay $1,561. 

He continued to negotiate with Double H until 2004, when Double H sent another letter saying he could renew his lease for a year at $1,561, but if he didn’t sign, the rent would be $1,611 per month. David paid the next four months of rent at $1,488, and Double H cashed the checks. After that, it returned his checks and sued him for back rent since 2003, plus late fees. Was the cashing of the checks an accord and satisfaction? Why?