>if exercised

You didn't have the funds for your contracts to exercise so TDA auto-sold if for whatever it could otherwise it'd expire worthless. As for what price the contract auto-sold at, after-market contract execution is delayed so the price you saw probably wasn't accurate.

For this reason, you should manage trading your own contracts at expiration if you don't have the funds to exercise them. This isn't the fault of TDA but rather you goofed.