Yes, that is the expected behavior.
Each of those blocks that you downloaded contains bitcoin transaction records spanning roughly ten minutes. All the Bitcoin clients which are generating bitcoins combine their computing power to
securely authenticate outstanding transactions using
linked time-stamps. The difficulty to generate a new time-stamp is adjusted every 2016 blocks, which is roughly two weeks, so that the combined computational power of the whole Bitcoin swarm will only be able to generate one time-stamp roughly every ten minutes. New bitcoins are awarded each time a time-stamp is generated to whichever computer generated the time-stamp. For the first 210,000 blocks or roughly 4 years, 50 bitcoins are awarded for each time-stamp. The number of bitcoins awarded for each subsequent 210,000 blocks is cut in half. I would estimate that your computer will probably generate at least one time-stamp everyday, but the rate will change every two weeks. Once you receive some bitcoins for generating a block, they'll immediately show up in the Bitcoin client, but you'll have to wait 120 blocks or roughly 20 hours before you can spend them.
