There's nothing wrong with that. At that time, there were only a few machines (presumably only satoshi's) running to mine Bitcoins.
The network does try to keep the blocks at an interval of 10 minutes. At that time, the difficulty was set at 1 and it is impossible to go lower than that, as per the algorithm that calculates the difficulty.
You say that difficulty can't go lower than that because of the algorithm, but it is much lower in the testnet, for example.
Is there a hard-coded minimum difficulty then?