I'd send an email or give them a call. You can find the info here:
Contact*-*Gibbs Lures
Most companies are stand-up and will make it right. I hope they'll tell you something like to go get a replacement at your local dealer and they'll comp them on their next order. Sometimes they'll want to see the plug back so they can improve their product.
Let us know how it turns out as we're always very interested in the experience our customers have with the MFGs. If you're not getting anywhere you can always bring it by the shop and have us a give a call (which we're happy to do as well) Gibbs is usually really good though, the few times we've received something in need of replacement or repair they've been really responsive and helpful.