You SHOULD be getting the 525 in one transaction, not as 500 in one and 25 in the other.
It wouldn't hurt to put in a ticket to ask about it. Given the length of time it takes them to reply, chances are you'll get the next grant before it's answered, at which point you'll have more data to work with.
It's certainly worth the ticket regardless, because you definitely want to be getting the grants you're due for the cards. There have been a lot of bugs with the system that they're working on (my balance was wrong for over 3 weeks before they managed to fix it) and they're not going to be able to correct yours if they don't know about it.
TY thought so