Milton Keynes Dons can go back above them by avoiding defeat at home to Sheffield Wednesday in the evening game, although the Millers will once more have a game in hand after that.
It came at a cost, with Mikel Miller suffering what threatens to be a season-ending hamstring injury, but the nature of such a hard-fought win should do them much more good than harm.
Smith's goal came 78 minutes into a second half when Rotherham had been piling on the pressure but racking up the "nearly" moments.
Smith had picked up the player of the season award, players' player prize and even the community player gong at the ceremony, which was held on the Thursday evening, and his although his manager was not delighted with the timing of event before it happened, he was able to look back and think maybe it did his start player some good.
"The obvious reason for (Smith's performance) is we had an end-of-season do - randomly in the middle of the season - on a Thursday night and hre won all the awards so maybe he felt good about himself,"said Warne.
"We're all human. Everyone wants to be respected and loved.
"His performance was right up there and he deserved his goal so I'm really pleased for him and we'll obviously have an end-of-season do on Monday and Thursday, and every week going forward.
"I appreciate in football you're up for criticism - that's absolutely fine, that's what makes the game great - but maybe having the end-of-season do on Thursday and having everyone coming up to Smudge and telling him how great he is and seeing how many goals he scored might have given him a boost and the same with all the players.
"Sometimes being nice to people helps."
Under the circumstances it felt like a really important win for the Millers, who received great support from the home crowd.
"The dressing room was buzzing," said Warne.
"They were really pleased with themselves. It's not so nice for Mikel being injured, but they're really chuffed.
"It was a relief. I don't feel cock-a-hoop, I'm not going to do a merry dance.
"There's pressure on me and the team to perform and I thought we deserved the win, it's not like we've nicked it, I thought our second half was really good, I just didn't know if we were going to score.
"Hopefully I'll enjoy it once I've had a sleep.
"We were excellent, I thought it was a good day in the sun.
"The fans were brilliant, which makes a massive difference to the players so I thank them for that.
"I just thought in the first half we were edgy, we didn't do our tidy-up passes very well, we didn't press and make it difficult enough for a very good team. If you give them time on the ball they're going to pick the right pass.
"We rode our luck early on because they had a great chance to score but I thought we had good half-chances in the first half.
"At half-time I just asked them to be a bit calmer, just make your tidy-up pass better and once you do, you have an opportunity to get at them. I thought we were very good in the second half and it was obviously the result we needed but it was also the performance we needed.
"The lads will get a massive boost from that. We can't control what other teams do but you give yourself a right chance when you perform at that level."
On wing-back Miller he said: "He's done his hammy, so I would suspect that's his season over. If we go into the play-offs he might be all right for the back end but I don't honestly know yet."