Steps to reproduce:

1. On the site wide calendar, select Week as the time period
2. Go to March 2010
3. Select March 8 - the week from Sunday to Saturday is selected
4. Select March 15 - the week from Saturday to Friday is selected
5. Select March 22 - 6 days from Sunday to Friday are selected in the calendar but 7 days in the title

I was expecting that the choice of starting day for a week would be consistent