Gray showing through porcelain crown. Is there anything the dentist can do? Is it something I have to pay for again? (Photo)

I just got a crown replaced today. My original crown broke two years and we just got the money to get it fixed. I was so anxious and happy. In the office the color appeared to match pretty well. Once I got home I noticed the porcelain crown looks gray. The dentist said my post was short and due to the root canal I would have to be very careful to not fracture the post, and kept telling me how difficult this crown was.I’m so disappointed because I’ve waited so long for this.