But the former Liverpool boss insists there is nothing to worry about and it is only a matter of time before he puts pen to paper.
Houllier finally takes charge of Villa for the first time in Wednesday night's Carling Cup clash with Blackburn after agreeing to become Martin O'Neill's successor nearly two weeks ago.
When asked if he had signed the contract, Houllier said: "No, not yet but it is okay.
"The word is more important than the rest. You mean physically? No, but don't be worried.
"This is not important - I think at Liverpool, I didn't sign until November or December."
Meanwhile, Houllier has insisted he has complete faith in Kevin MacDonald, who was caretaker boss for the opening seven games of the season.
MacDonald declined the opportunity to be part of Houllier's first-team backroom staff and will revert to his role as reserve team coach.
Houllier said: "I understand why he didn't want to be there. Let's be honest, he was a bit disappointed because he was interviewed like the others.
"But I trusted him to be my number two and I trust him to be the reserve coach which, to me, is someone you work with all the time. He is part of my staff."
The Frenchman wants Villa to emerge from their comfort zone and start winning trophies under his stewardship.
The Carling Cup brought Houllier his first trophy when manager of Liverpool in 2001, the Reds defeating Villa's local rivals Birmingham in the final in Cardiff.
Houllier believes that success gave the Reds the confidence to enjoy a successful spell under him.
And the 63-year-old is aware just what ending a 14-year trophy drought would mean to the Villa supporters.
Houllier said: "Winning a trophy would be fantastic for the club and a huge reward for the fans. It will come.
"Maybe what the club needs is more ambition and to show its fighting teeth. Sometimes when you are a good club, everything is fine and the comfort is there.
"Maybe what we need is to get out of this comfort zone and get results a bit more.
"The passion is there but the ambition to win things would do well at this club.
"The image is a nice club. We want to be a winning club, and a nice winning club."
Houllier continued: "Winning that first trophy with Liverpool was crucial. It took a lot of pressure off the team. It came as a relief. We had actually won something.
"Even Chelsea lifted their first league title after winning the League Cup.
"I remember speaking to Jose Mourinho and saying, 'Don't neglect this cup because, if you win it, on the back of that, confidence grows'.
"That is exactly what happened. After that we practically won everything at Liverpool and we want to win something at Villa."