Not all. I went to my advisor with a project that came out of my work prior to going back to school for the PhD. However, it really surprised my advisor that I had my own topic. He did agree with ith, though, and I carried it through.
Most graduate students don't have any idea for a project, so they're glad to get a project from their advisor.
If your advisor is not familiar with the research behind your project, how could he confirm that it is original and a contribution to the field? He must have had some prior knowledge of your project and your project must have been related to his research in some way.
I have been told that it is extremely rare to have any earth shattering contributions in a PhD dissertation, so kudos to you!