United are currently seeking a replacement for the sacked Terry Venables and the former boss has eyes on a second spell at the club.
"I have just a sneaky feeling deep, deep down that some time along the way I might get back there and manage them, and if I do I will be absolutely delighted," O'Leary told BBC Radio Five Live.
"I didn't want to leave the place and if I was asked again, if I could sit down with the right people and talk to them, yes, I would take it again without a doubt.
"People say I spent £90m but I recouped over £70m of that. The gates over the four years were record gates.
"In the Champions League we made nearly £20million, and the year before that in the Uefa Cup it was about £7million.
"The commercial side of the club had never been bigger. We bought well and we sold well and to get the debts we have, I mean the figures just don't add up."