Henderson was unluckily dropped after an impressive debut two weeks ago against Accrington, with Ryan Taylor coming back in for Saturdays win at Burton after a groin injury.
But Watford loanee Henderson came on for the final 18 minutes, setting up the equaliser for Marcus Marshall just three minutes after entering the field.
"It was a superb ball in for the goal," said boss Ronnie Moore. "It is more competition and gives me food for thought."
Moore may go to the South Coast and play three strikers in a positive move to try and grab the Millers first away league win on a Tuesday night all season, ending an unwanted hoodoo.
Elsewhere, Tom Pope is set to remain with Port Vale for another month despite the in-house turmoil at Vale Park.
Boss Jim Gannon and coach Geoff Horsfield both left the team bus on Friday on route to Aldershot, with Gannon joining up with the squad in the evening whilst his assistant stayed away.