[Rhythm Heaven Fever] Dark 1px Line Around Custom Textures

[GregEmu]

Whenever I load custom textures into Rhythm Heaven Fever (hd textures if that makes things different here), all the custom textures have a very thin (1px) line around the edge. I have confirmed that this is not a problem with the textures themselves, as when I used the default textures from Dump as custom textures, the stroke was still there.
Examples:
(left is original, right is custom)

[attachment=18242][attachment=18243]
[attachment=18244][attachment=18245]
[attachment=18246][attachment=18247]
[attachment=18248][attachment=18249]