Rasmussen on Pennsylvania

Rasmussen has conducted three polls of Pennsylvania during the last week. The first poll it released last Monday showed this spread:

Obama 53
McCain 46

The second poll was released on Thursday:

Obama 51
McCain 47

Today's poll by Rasmussen tells this story:

Obama 52
McCain 46

In other words, within one week, Rasmussen found Pennsylvania to be 7-5-6. These are random fluctuations in a static race.