Well, I think, he is an adult and obiusly he is really responsable, but money wise, if he keeps asking for money to you, I would say something.
It's like people that smokes and don't make it to the next pay check; I'm sorry but if you ask me for money I'm gonna say quit smoking; that is the way to make it thru the month.
It's a touchy issue though; I hope you can find the best moment and ways to talk to him about, even though he is an adult, he is still really young and might not look at the future so deeply like an older person.
Your are his mom, nobody in the world would know him and love him better than you.
Pm me anytime if you need to vent
~hug~