Rent had an 11.3% drop this same week last year. If you look at the history for Rent's attendance, it's consistant every year. An increase in attendance for at least the two weeks before Memorial day, a drop of 10-25% every year for the week of Memorial day, and then increases again for at least two weeks after that.
It's the same every year, just as it is with most shows (With some exceptions). Just click on any show on the "Grosses" page and you can see that show's history.
I don't know if it's because of Memorial Day, the letdown after the increased sales burst generated from the publicity of the Tony nominations, or the lead up to the Tony awards themselves. It's probably a combination of all three.
Art has a double face, of expression and illusion.