I remember when I signed up they said there would be some kind of $25 hold charge or something. They said it should never show up. They supposedly credit it back after they verify your credit or something to that effect. At any rate, it didn't show up on mine so, you could be the same way.
If you really are wondering, why not just call customer service and have them explain it to you?
as Mark stated, its best to call and ask.. But if it is $25.00 EVEN (no change, etc) then it is just a "Hold" (It will come off hold in 2-3 business days) to make sure card is good and valid, why $25? I dont know, thats how Directv does it.. If its $24.xx or $25.xx (change) Directv usually charges $19.95 PLUS tax for "Handling" fee, but if I recall D* Website has been waiving that fee for months now..