Steve was sent off after a collision with Harris, who by then had lobbed wide of Steve's goal with the score at 3-1.
That meant that the Hammers had the huge task of chasing the game with a man down and, some would argue, effectively ended the game as a contest.
"It was quick; the ball has bounced and he has gone to lob me," says Steve.
"I just jumped in the air to try and get the lob and he seemed to run into me.
"It was just a collision, and I didn't mean to take him out to stop him from scoring - it was just one of those things.
"I have gone to jump for the ball and I am not so stupid as to try and foul him - I am not like that.
"The ball seemed to hang up in the wind a bit and when I got there he has done well to get it over me, and I just stood there to protect myself.
"I was trying to tell the ref that it was outside the area and I didn't really know he was going to send me off.
"When he showed me the red card I thought 'I'd better get off the pitch' and I tried to get off as quickly as I could.
"I jogged so the lads could get back playing again, because we were 3-1 down and we needed to restart the game.
"To be fair, it killed the lads, the sending off; it is a nightmare that I have had.
"It is hard with 10 men but that is my fault, really."
The dressing room is a lonely place when you have been sent off and Steve adds:
"The kit man was in there talking to me and then I watched the last five or 10 minutes of the game, that is all."
Millwall had certainly ridden their luck earlier in the game when a Christian Dailly own goal - the fourth West Ham have conceded this season - nestled in the bottom corner following an Ifill cross.
Says Steve:
"I think the ball sort of died and it hit the end of his foot; it was windy and it was unlucky but it was the same for both teams.
"We need a scrappy goal like that but we don't get scrappy goals - we could do with a couple of them."
The fact that Steve Bywater had earlier saved a Harris penalty after Matthew Etherington was adjudged to have fouled Ifill suggested, perhaps, a different outcome might have been the order of the day.
Yet again, though, heroics by Steve from a spot kick did not lead the way to a victory.
"At Sheffield United I saved a penalty but we ended up not taking the three points and that is what has happened on Sunday; I am devastated," he says.
Steve is so disappointed that he and his colleagues couldn't give the 2,869 travelling fans what they wanted, and he adds:
"Millwall are a hard working team; they are just grinders, and that is what they have done, ground us down.
"I thought we were going to win the game but everyone was gutted after the game.
"The fans have come and shown their support and we haven't produced for them."
As for the off field goings-on, with mounted police and officers with riot shields overseeing a minority of West Ham supporters, Steve says:
"You don't really notice what is going on around the pitch, you just need to do your best.
"Now we just have to try and win our next game."