Peers review your FMLA certification. absent four days.

I have worked with the employer for 3 1/2 years without attendance or performance issues. I had some personal problems and was overwhelmed and stressed. I called in to my manager, who is also the benefits manager, explaining I was having some personal family problems. I said I would be off for two days. The next morning my manger called and asked me to provide documentation as to why I was out. I did not want to go into detail about my personal issues so I went to visit My primary care physician. My doctor was aware of my family circumstances and wrote a doctor's excuse for the remainder of the week. I provided the doctor's excuse to my manager. My manager called me on the 3rd day (thursday) and said I would need to complete FMLA paperwork detailing the reason for my absence. I was out for a total of four days. Although FMLA is confidential, the paperwork is reviewed by my peers and direct supervisor. I feel like it was an invasion of my privacy. Is this legal?