Many years ago, I had that same speed problem with an LP of Herrmann's THE BRIDE WORE BLACK. I'm pretty sure that was a boot. I wonder what this BONE TOMAHAWK's excuse is.
I doubt that it's any kind of any error (other than in the lack of a notification to the purchaser). A number of classical LPs were mastered to be played at 45 rpm in order to improve the fidelity of the playback. For example, in 1979, Angel Records issued a number of such LPs in what they called their "45 RPM Sonic Series." Some, by necessity of the added time, had to be 2-LP sets.
Bone Tomahawk is a very brief score so I assume the 45 mastering was done for higher fidelity. (Stylotone's Twisted Nerve and Khartoum are both at 45).
It just would have been nice if they had mentioned it somewhere on the cover or label.
