In Freebitco.in faucet, the base reward increases when betting on events and playing multiply BTC game (paid rolls), as well as when buying lottery tickets. The base reward of faucet is equivalent to $0.002 in BTC, but this does not include the added bonus amount based on each player's unique betting history. You get 50-60 satoshis per roll probably because you gambled a lot more than some other users, so you have a bonus added to all rewards.