Don't worry, it's pretty standard policy; both from a realistic perspective as well as a game perspective.
Realistically casino's like to make money, not give it away. So if a player is 'on a roll' the management will often persuade the person to refrain from more gambling by offering certain accomodations etc. etc. (A bit of the 'take your winnings and go' but with friendly smiles and pats on the back).
From a game perspective, the developers wouldn't want a lowlevel character running out with 100000 Chips on day one, just because luck was in his favor and he spent the last 8 hours on a slot machine. So they place a maximum on how much you can haul away from the casino every day/week. This works two ways in that the player doesn't suddenly have tons of cash but also a nudge out the door to go do some quests and exploring the game instead of playing 'Vegas Poker Online'

At least that's my take on the situation. So don't worry, you won enough for one night but you will be welcome to gamble again at another time.
Greetz,
Milt