If by dimples you mean a protrusion or slight bulging in the veneer of the plywood then I think you need to determine why it is doing that. Could be a void in the inner plys. If it is soft and gives slightly with finger pressure it is probably a void. You can slit and fill it, or use a syringe. If all is sound and you have a slight "depression" instead, and you're going to paint, you could fair it after glassing with a goopie mixture. If it is none of these, but a slight fault in assembly, you will have to consider other options, or... you might have to live with it. There are numerous possibilities in faults and solutions. I'm sure others will come up with more.