Done Total Knee Replacement. Fever, Chills, Tiredness. Normal?

I had a total knee replacement 4 weeks ago today (right knee). For the most part my recovery seems to be on track, but I have been having low grade fevers and chills (nothing higher than 99.7), mostly in the evenings since surgery. At 2 weeks post-op, my surgeon told me this is normal, but is it normal at 4 weeks? I m only taking pain meds at bed time, and ibuprofen during the day. I also tire very easily. I see my surgeon next week, but wonder if I should try to see my primary before that.