Depends on the before and after snapshots of your credit report.
Unfortunately the monitoring solutions don't catch every single change, and some are summarized as they don't check real-time. I'm still trying to figure out why I took an 18 point drop a couple of months ago as I had on the order of 6 changes hit the report at the same time according to my monitoring... fail mode. Pretty much gave up, shrugged and went on with life. Can't get caught up in the minor ups and downs over the short term, long-term focus is where it's at.
Anyway in general a change in balance can affect both overall utilization, individual card utilization, and number of cards with balances. Any one of these 3 or some combination can drop one's score, and depending how high your original score was, 10 points isn't out of the realm of posibility for any of them.
