I believe as others have pointed out that the system looks to point at least 2 things to provide constructive feedback on and since you have as close to a perfect FICO score I have ever heard of it is truly nit-picking.

I noticed that my score dropped when I paid off my mortgage years ago and dropped again when the loan I co-signed for my son's car was paid off, leaving nothing but CC lines of credit - always paid in full each month. This seems counter-intuitive to me but has not negatively impacting my hobby of getting new CC's as I have yet to be turned down for a new app.