During the last months the price has already went up very far.
Now a lot of people are afraid that a bubble might develope. But since there is no sign the price might go down, they do not sell either.
I suspect the price to stay constant on this level now for a while.
Current levels can't be considered a bubble, or a bubble in-the-making. If we shot up to $1700-$2000, then yes, it would be a proper assumption, but not at current levels. I think the price we are seeing now is just about right with demand for a big part coming from people looking to escape the tyranny of their governments. Bitcoin for these people is a great escape from their governments, plus it also offers a great investment opportunity. People would be stupid to not secure a part of their wealth in Bitcoin.