Hi Mary, and welcome to the board!
You're still very early in your recovery. Hip pain could be from a lot of things. It could be that you're using muscles differently due to pain or caution of your back. It could be nerve irritation, which takes a long time to calm down. I don't know if the hardware itself could cause it, but maybe it's pressing on a nerve. Try to pinpoint the times it acts up, what you're doing and how long it lasts. Try to describe it and note whether it radiates in any direction. Those are the things to tell your doctor so he can best determine the source.
Are you walking? That's the best exercise for post-fusion. It's not too stressful to the spine but it gets blood circulating around it, which is essential for the fusion process. How are things otherwise? Are you still having much pain? Is your doctor keeping you prescribed with appropriate pain meRAB?
I wish you the best. Keep hanging around and reading. There are lots of us who have had fusions and can answer many of your questions from our own experiences.
Emily