Paste layer, rendered in Cuprum:

Tracespace.io:

KiCad's gerber viewer:

And finally, gerbv (obviously broken):

The lines causing these problems are all something along the lines of:

20,1,$1+$1,$2,$3,$4,$5,0X25.4+90*

Yes, It's weird and not actually needed, but CAD programs are notoriously stupid when it comes to the sort of output they sometimes generate, especially for things like gerbers.

In this case, the rotation (the final argument) should be 90 degrees, as 0x25.4+90 = 90 degrees. However, I manually measured the angle of the odd pad rotation gerbv displays and it is 36 degrees off from the correct 0 degree angle.

25.4*90 mod 90 = 36. The only way rotations would end up like that is if gerbv thinks 0X25.4+90 = 2286, which it isn't, it's 0. Given that gerbv is the only library/program I can find with this problem, I think it's safe to say this is a bug specific to gerbv and not something that can be blamed on the gerber being 'unusual'.