There was uncontradicted evidence presented by plaintiffs that although they knew on August 27, 2002 that their tenant had been found lying incapacitated inside her apartment and was brought by ambulance to the hospital, they lacked knowledge that she had sustained severe injuries from falling down stairs inside her apartment, and that the tenant provided no information which would lead plaintiffs to believe she held them responsible for her condition. In these circumstances, the IAS court properly concluded that defendant had not shown that plaintiffs' delay in notifying defendant of the incident until June 18, 2003, shortly after the tenant commenced the underlying action, was unreasonable as a matter of law ( Argentina v. Otsego Mut. Fire Ins. Co., 86 NY2d 748). Furthermore, taking all the circumstances into consideration, plaintiffs' apparent failure to conduct any inquiry into the tenant's condition did not render their excuse unreasonable as a matter of law.