"We got lucky at the end," he admitted after the 2-1 win at The Valley.
"It was a definite penalty and I am obviously delighted the lad missed it.
"We have improved as the season has gone on and we need all our players to be fit and available. We kept our belief and it is a great three points for us as this is a very difficult place to come to.
"My remit when I came into the club was to keep us in the Premiership and 12 players have gone and the wage bill has come down drastically.
"We now have a nice close-knit squad who get on well with the job they have to do."
O'Leary was also delighted that Colombian striker Juan Pablo Angel was able to play in the game as he faces a journey from hell in order to play for his country in the World Cup qualifier against Peru on Wednesday and faces 35 hours of flights.
"I don't think Juan will be back for our game next Saturday but I am at least happy that he was able to play in this game," he added.
O'Leary was non-committal about talk of a Villa take-over by a consortium headed by former Manchester City player Ray Ranson whose initial £30million bid for the club has been turned down.
"We can't be concerned with, or have any influence, about peripheral things going on around us. We just have to get on with the job in hand."