So support got back to me today and they don't see any adjustments to my balance, so they think it's just a known display bug. I replied that this wasn't two different pages showing different amounts, but the same page (the balance at the bottom of the browser window) going down during the day, which seemed to be a different issue.
They replied that they checked into my account and no refunds (beyond one from yesterday morning I received e-mail about) were issued. I don't feel that this is a good explanation for a balance going down (versus going up one place earlier than it does another, which we've seen before when the various Akamai servers are out of sync), but I don't think there's much else I can do except watch things and take screen captures...
As an aside, both e-mail responses were prefaced with an apology for the delay in responding - which wasn't necessary as I only submitted this ticket this morning - so I think it must now be boilerplate text in their responses
