They do have great customer service, but nothing is free....
Sent in a pair of Brine's a few weeks ago. The plastic frame right above the lense had cracked. I figured they would replace for free. I get the e-mail from Costa: $49.00 for new frames. WTH??
I call Costa, and they tell me they conclude the damage is not from "normal" wear and tear. Bummed out, but wanting my Costa's back, I authorize the $49.00. They fixed them nicely, sent them back quickly, and polished up my lenses. All in all - I was happy with the service, but felt a bit cheated by the whole 'lifetime warranty' bit.
I've heard that lenses are hard to get replaced for free. However, it sounds like you have a good case. I just ordered some Costa Wingman's (aviator as well), and hoping that doesn't happen to mine. Love em. My go-to's for shotgun shooting, and dove hunting this fall.
[This message has been edited by PFG (edited 6/15/2011 10:47a).]