Bruce:
I had similar symptoms about 3-4 weeks post-op. Woke up feeling crappy on Monday, fever, chills, hurt all over. After monitoring it for 2 days, I went to my family doctor. He ordered blood cultures, which were negative. However, he said he's seen enough endocarditis that he didn't want to assume it wasn't. At least one of his patients over the years has died from endocarditis -- and she was an RN, I believe he said without any further details.
By Thursday, I was back to normal -- it as like a veil had been lifted from over my head. Still sore from my surgery, but no more fever, chills, etc. My doctor surmised it was a short-lived viral infection, due to my immune system being compromised by the surgery.