Low T a symptom of something else?

My wife doesn't beleive that I just got low T from nowhere

I'm 35, married, with three kids. Never thought I had a problem with low energy. Used to work out and have always worked long hours. I recently had my T-levels checked and they found my Totals were; Total-T *49* and Free-T *3.2* I've never researched these numbers before, but my doctor looked shocked and asked how I even went to work everyday. Anyway, my wife wants me to do more tests because she thinks that there is no way to have levels this low at my age and everything else (other tests) show nothing else. Has anyone here had levels this low, or similar?