Odd Letters from Social Security Administration

I work in HR benefits management and just got two odd letters from the Social Security Administration about two of our employees.  They were basically performance appraisals.  They asked questions such as "did the person show up for work on time?", "did they need extra assistance in performing their jobs?" or "did they need additional time to perform their duties compared to employees in similar positions?"   I have never seen anything like this before in my very long career.  One person is retirement-age but the other is not anywhere near old enough for OASDI benefits.  Does anyone know what on earth this is about?  Has SSA potentially "outed" employees who might be applying for or receiving disability benefits?

Have you done anything to check whether the letter is an authentic act of the Social Security Administration?