Hello Kray and thanks for your service.
They may be checking to ensure you were paid correctly all your benefits; just my opinion only.
Since you are a retiree, you should be able to call the 1-800 DFAS number that handles your retired pay and they should be able to tell you something as well.
Back in Sep/Oct 2006 before "ebenefits", I got a letter from DFAS retiree section stating they were reviewing my files in conjunction with my VA rating at the time as I may have been underpaid; about 3 months later, I got a direct deposit over $4500.00; so I called them again just to make sure there were no mistakes and was informed that is the amount I was underpaid and my retiree pay is correct now.
Just a note, I went from 60% VA rating in 2005 when I retired to 80% in late 2006 and that may have been the reason for the review.