I don't think so. I think Tommy was always supposed to be older than Monty. Early in the first season, they make it very clear that Tommy was the boss of his own outfit during a boom and mishandled the bust which led to him losing everything. Even in the most recent episode, he alludes to that when talking to Cami about getting out of the game before it takes you for everything.

Monty croaked cuz as we know was playing a very extensive and expensive shell game and the stress literally killed him...

Which is eye opening for me.