Are you a new subscriber?
New subscribers will have their allowance reset daily for the first 10 days (HN9000 modem) or 20 days (HT1100 modem). This is done so as to allow you to get all of your computers and devices updated without impacting your allowance.
Honestly, the reset can occur at any time.
Another potential reason would be that for some reason the meter had yet to connect to the Gateway and get into sync with the modem and the store modem value was out of date.
This 10 or 20 day daily reset SHOULD have been described to you in a "Welcome to Hughesnet" email.
In truth this is something extended to new users that has really has cause "issues" with some folks that find it a deceptive tactic.
Proof I guess that no good deed goes unpunished.
People KNOW that it is a capped service, look at the usage meter ... and in some cases at least feel that they are ... getting away with something .... then howl like a banshee when it ends.