IME, some FFLs just like to be dicks. Some also will not accept an incoming from a non-FFL. Some like to play the "I won't show you my license until you show me yours first" game. Some have made up a stupid multi-page form they expect another FFL to fill out when shipping them a firearm. Some will hold a check for 2 full weeks, despite the fact that, for decades, the max turnaround time on a check is 3 business days. Shooters Outpost in Hooksett, NH won't sell mags or ammo without an ID (even if you are obviously WAY over the minimum age). People like that can make up whatever additional rules they want for their business, but we already have too many restrictions without FFLs making up more rules. I won't do any business with FFLs like that if they make up more rules not based on any law.