Gregor made the case?

The window before the make out session you mean. He's spraying the window so that when he sprays the case people won't say what's that paint smell ?

So he had to make it at the last minute in the van with Dierdra\before the shootout\right after? I love this movie but isn't that a bit of a stretch even for a snake like Gregor? Unless he had no other opportunity.....