Maintenance Not Adding Up

I created a spreadsheet in excel tonight of all my ship designs in a game I'm playing including the Maintenance and numbers for each design. I came out with ~140,000 Mineral Maintenance for the combat ships and units in my empire. Granted I left out some auxilary designs they shouldn't add up to more than 25,000 minerals. Yet the Empire Options screen says I'm using 237,000 Minerals for Maintenance. Thats not even close, so I started going through figuring I missed something. I added my spreadsheet numbers and compared them to vehicle size statistics and I come out right on. Then I figured, maybe the ship design screen is mis-stating the maintenance cost so I started going through individual ships and comparing what they say for maintenance and it was off for a bunch of them but it was actually lower (took me a minute to remember I have crystaline restructuring plants in several systems). So now my numbers actually make less sense.

So I guess I'm just curious if I am missing something or if maybe I ran into a bug?