Kevin was touching up the Demon repellent writing on the windows by the sink on Garth's boat. Just before Crowley showed up, the windows were blown out. When Sam and Dean arrived to talk to Kevin about the third trial, you can see after Dean turns on the lights the windows that were blown out are now intact. This could be an attempt by Crowley to cover his tracks or a continuity issue.
Cass tells dean back when they first meet chuck that any harm can not come to a prophet or arc angel will show up, so either they are all gone by the time this happens to Kevin when Crowley shows up..or the made a huge error in the writing.