New cartridge reversed my stereo

[YngwieJMalmsteen]

edit: mods if you get a chance please move this to dedicated source

I just installed a shure m97xe and it sounds wonderful, but I somehow managed to reverse the stereo. My old cart (audio tecnica A88E) was was arranged arranged like this:
blue . green
white red

So guessed that it was:
left ground . right gr.
left . . . . . . right
because that makes complete sense.

Now the shure looks like this:
...RG
L
...R
LG

I thought I hooked it up right, but then everything was backwards! For now I switched the L and R going into the amp because I'm lazy (mounting and mounting cartridges is not my idea of fun), but I'm wondering what I did wrong. Does switching the ground channel reverse the stereo too? Is there any reason other than pure nerdiness to fix it?