I too thought you did not get nights for free stays, but my account currently says something like:
Nights Stayed 10
Bonus Nights 18
Now, 10 of the Bonus nights are from my Chase Visa card, but I can't figure out what the other 8 Bonus nights are. And they are strangely equal to the 1 + 1 + 1 + 2 + 3 nights I stayed on free stays this year.
Are you sure your card doesn't give you 15 nights and then the 3 night stay was in the double points period?