Why are some people surprised at this? Do you also believe that dead people cant vote and illegals cant get welfare. I was involved closely with a state election here in NY in 2010 and from a misunderstanding the Democrat though I was on his team. They would call me before every debate and ask their supporters to fill the hall.
Also, people that help out, and volunteer are often rewarded with invites to special events like that. Because of my volunteering for various candidates, I have been invited to events like a Sarah Palin fundraiser, a speech by Laura Bush, several Arnold events (I know, I know), a McCain speech, etc. Volunteers and donors get rewards like this all the time. Volunteers deserve it.