I have never, nor intend to ever accept a shop I completed in the past, where the regular fee was lowered. If, though, the prior visit(s) had been under any inordinate circumstances, it would depend upon the situation. The most urgent job I recall, involved lunch that needed to be shopped in the next hour. I requested and received an additional $8, for a total of $15 and $13 for food; all later work reverted to the normal $7 fee.