What happened?

I just purchased new a VPI Classic 3. Upon opening the box and removing the platter the aluminum thin disc that sits in the inset on the bottom fell off. I could either leave it off because I'm not are what function is serves or glue it back. Thoughts?
Contact VPI. I'm sure they will send a replacement. I would not try to glue it back on. It might unbalance the platter. It may be unbalanced without the insert as well.
Contact the dealer. If you're not satisfied with what they offer to do, contact VPI.
Follow up....

I called VPI and the plate's primary purpose is extra dampening. Mike wasn't there but they offered to replace the platter, or I could leave it off or put on a couple dabs of construction glue and put it back. I'm going to leave it off for now.
I would only take the suggestions of Mike or Harry.
I would ask them for a new platter.
send it back...get a new one.
I would not mess with it. What happens when you want to sell it in the future? Send it back for an original factory replacement. That's the only think I would consider.