Remember, Roger is from Reno & has already conducted his business with the jewelry store owner. There is no reason for him to expect anything. Or is there? Also, is Jacob & crew beginning to act like thugs themselves? It's a fine line.
Well this was in 1937 so the government was more concerned about gangsters and such not paying taxes but not watching for found treasure so much.
The jewelry store owner probably doesn't suspect too much now, probably thinks Roger is just buying some bulk gold BUT if Roger doesn't come back into town for a long while he will get suspicious and wonder what happened to him!!