I was able to on iOS 6 but it took awhile to click the x in just the right spot. Had to stand on one leg, while jumping, and holding my tongue to the left. (The last bit was just a joke but it was still difficult to close it out.)
I was able to dismiss the first notice easily but the 2nd (final) notice I had a heap of trouble clicking on the sweet spot until I zoomed in on the iPhone 5 iOS 6.1.4.