Yup, koa does that, especially koa or other hardwood tops. They just take a while to open up and relax. Most people give up on koa guitars too soon. My 2007 all-koa 424-LTD was nice when I got it and has become even nicer over the years. My 2006 koa/spruce GS has also opened up nicely, but with a spruce top that happened pretty quickly.