Gosh, not fair, you going back on topic just when I wanted to retort to some of the earlier off-topic grey/brown nonsense again. I shall refrain. (And bide my time...muahahahaha.)
Seriously back on topic, BINK, I'm serious - how much of that is a real hat ad - I'm really having trouble telling if you made the whole thing up or just some of the words. (Color me stupid.)
I'm just thinking if most of that (other than the obvious edit for the "Can't we all get along" touch-feely part) is real, then right there that's a credible point for explaining the possible use of an allegedly grey hat.
I.e., in ROTLA, they didn't seem as bent on keeping Indy in his 'trademark' look (since it wasn't really a trademark yet), as evidenced by him spending SO much of the end of the movie in a German uniform - no fedora, jacket, not even khaki. Just grey. (Although he got to keep the epaulettes somehow.) Likewise, they put him in a non-brown suit at the end, and apparently also in the plane. (Notice I don't mention the hats.) Point is, in the first movie, they may not have cared to keep him in earthtones (I mean BROWN folks) all the time...which would make a blue/grey based outfit for traveling and government meetings a plausible wardrobe decision for the first movie.
I don't think the TOD and LC costuming decisions have any bearing on this. In TOD once he hit the plane he spent pretty much the whole movie in one set of clothes (I forget, did they lend him a blazer for the Snake Surprise?), and by LC they did put him in brown-based suits, and I assume this was to keep him as close as possible to his (by now) trademark look - at least by sticking in the same color pallette.
Why is this not off topic? Cause if Bink's ad is real - the bottom part, I mean - it says something distinctive and highly relevant - "Brown for Dress, Grey for Travel". If that's a true ad, it is indicative of possibly common style sense that we have forgotten or no longer applies today, but could explain the reason why a non-brown hat may have made an appearance in the first movie, which at the time was probably going to be an ONLY movie, and there wasn't a 'trademark' look the were trying to keep true to.
Bleah. Now I feel cleansed and detoxified...where's the coffee?
J
EDIT:P.S. I'm also on Fedora Lounge, but not a frequent poster there. Would someone else who more familiar w/ the Lounge like to take this similar ponderance over there? That board is FULL of folks WELL-VERSED in the styles of the day - and I think that has way more bearing on answering this question than many of the ideas we gear-minded folks have. Seriously, wait till you see them at the QM! Zowie! (This is like the Mythbusters trying to host Queer Eye For The Straight Guy. Those teams have very different strengths and skills. Likewise, I think this is a problem for the more fashion-minded.)