Is it ethical for a Law Firm to deduct a $500 Expert Witness Fee from a Settlement if the case never goes to court

I am the claimant in a personal injury lawsuit (rear end collision, not at fault). The At-fault-drivers Insurance refused to settle the Demand of $438,000 for injuries, pain & suffering, etc. for over 18 months until My Attorney filed the case with the courts. Just before the court date, they decided to settle by sending the full $ value of the policy, $25,000. My Law firm is holding over $6k in Trust to pay medical bills once they negotiate reduced rates. They also took their $10k cut, and then another ~$1250 in additional fees, court costs, filing costs, etc. In that additional fees, they charged me $500 for an Expert Witness even though we never went to court and no Expert Witness ever testified. Is that ethical, or should I attempt to recover it...?