You're exactly right. It's the consistency of the lead. And McCain seems to be doing nothing to try changing that.
McCain's gains could be statistical noise. Next to the younger and dynamic Obama, he has problems gaining attention. The MSM is making sure nothing will happen for him. It will be Obama All The Time on all the channels.
"Show me just what Mohammed brought that was new, and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." - Manuel II Palelologus