Babbles,
I'm going to guess that it is due to your credit mix. FICO likes to have a diversification between Revolving, Installment, Open, and Mortgage. If you've recently closed one of these 4 types, it can negatively affect the magical FICO calculation.
Anyone else wanna take a W-A-G?
Ruff!
11/14/07 TU 567 - EQ 561 - EX 577
11/29/07 TU ??? - EQ 573 - EX ???
12/10/07 TU ??? - EQ 579 - EX ??? - 60% util - OOPS!