You see, Putin's position always was the real politics, not idealistic. Russia does not have messianic objectives in foreign policy to change the world to the best, to teach everybody freedom nor turn all peoples into any superior way of life. Russia works for its interests. Russian regime would like to have such PRISM for itself and Putin does not like to demonstrate obvious hypocrysy. So there are no ideological reasons of saving private hero Snowden.
On the other hand USA establishment for some reason looks really mad about that story. USA can go berserk like after Sep.11 ignoring common sense, violating laws, bombing and invading countries and killing people. So your bravery can cost you.
On the err... third hand US politicians traditionally use Russia as an enemy in their rhetorics and proved to be perfectly conservative in that no matter what happens outside US. So Russian diplomacy with US plays a bad baby who gets candies from time to time for each while of being obedient. Now Russia plays naughty but not naughty enough to get brutalized.