On my classicals the G-string is the SMALLEST of the wound strings.
Most of the time I find the opposite...the G string seems muted in comparison to all of the other strings.
I wonder if the UST pickup (just an assumption it's a UST) might be a two part item, one part for strings 1-3 and the other part for strings 4-6. That might explain why the G string seems loudest, it would be the only wound string on that part of the UST. Just a guess, though.
If you bought the guitar from an authorized Washburn dealer you should have a limited lifetime warranty. I would doubt that it would be necessary to send it back to the Washburn headquarters, they would probably refer you to a music store that is an authorized dealer for evaluation. It might just be a simple adjustment.
Hope this helps a little.
Dugly