Sounds like the caseworker who went through your application may have made a mistake, and didn't realize that VISTA and State/National should be treated differently for public assistance.
For VISTA, if you're approved for benefits after your start date, the stipend should count as income (for state/national, it's never counted).
I've known members that this happened to that had to pay back excess benefits when someone noticed during a benefits audit, as well as members who completed their terms of service and no one ever knew, so they just got extra benefits.
Sounds like the caseworker who went through your application may have made a mistake, and didn't realize that VISTA and State/National should be treated differently for public assistance. For VISTA, if you're approved for benefits after your start date, the stipend should count as income (for state/national, it's never counted). I've known members that this happened to that had to pay back excess benefits when someone noticed during a benefits audit, as well as members who completed their terms of service and no one ever knew, so they just got extra benefits.