You're probably right, which is why Kirk is in the Watch List and I'm rather skeptical he'll move up the list. However, the district is Dem-leaning (GWB took 46.9% in 2000 and 47.2% in 2004) and his opponent his year has actually raised a competitive amount of $374,159 (Kirk has raised $1,635,450). While it's difficult for me to imagine Kirk becoming seriously at risk, that's enough to get on the Watch List for the time-being.
Keep in mind that the Watch List is exactly that: Seats that are basically Safe right now, but are worth watching.