Maybe. Go see a trademark lawyer in The Republic of Austin and find out. When you get a cease and desist letter from an attorney you need to go see your own attorney and not rely on "several people" who likely know bumpkus and could give you a bum Texas steer. Obviously the attorney thinks you infringe, and the designer thinks you infringe and if you can't afford to defend yourself, it may be "game over" for you. Now, if you hire a good IP litigator, and Austin is home to several of the country's very best, your attorney will perhaps determine the attorney is "bluffing" and call the bluff for you. Until then, however, with you on your own relying on "several people" for legal advice you are likely SOL.
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
There was a similar case brought involving Urban Outfitters and a heart design being stamped out of tags shaped liked the fifty states and I believe a court ruled that there was no uniqueness or copyrightable element to that deisgn. Take a look at my blog post about protecting jewelry design,
but right after that go see an IP lawyer in your area to get the in-depth advice you need to protect your busniess.
The answers given are informational only and do not constitute legal advice. Please feel free to contact me if you want to obtain legal advice from me.
Maybe but without a bit more information its hard to say for sure. It comes down to what element(s) of the design they are claiming are copyrighted and whether your design is copy of that element. You should talk with an IP lawyer. Feel free to contact me. I'm an IP lawyer in Texas