By the way, I just re-watched the Season 1 Pilot tonight, and one thing I had completely forgotten was that Philip was actually in the garage, with his gun at the ready, when Stan broke in to check the car out, and Stan just missed catching Philip with his flashlight, as well.

This definitely puts a new color on Philip's and Stan's interactions since then, since Philip (and presumably Elizabeth) have thus always known that Stan had at least some kind of gut feeling that P&E weren't on the level.