Seems fair both ways to me. That doesn’t seem an unreasonable amount of pay for a day’s work, as even if the ‘final product’ is only a minute, it will still have stopped him from doing much other work that day. Contrariwise, if he’d been asking for any more, the client would have been able to find someone else to do it just as well at the original price, since the requirement is basically ‘clearly spoken’. Wouldn’t make sense to get Ian McKellen in to interpret this bit of acting work.