I've always translated the warning result in a job as "job completed, simply not as it was configured". So, if the job is not explicitly failed, I'm not taking too much care of warning results, backup has anyway saved my VMs correctly.
There are too many reasons a job will fall into the warning state: IDE disks in hotadd, nfs datastore, to name some of them. If I know for example a VM has a ide disk, I will not take care of the daily warning.
EMEA Evangelist @ Veeam Software
Veeam VMCE #1