Make sure that it is not backwards (don't know whether that is possible with an M, but it is with some).
Also, ensure that the metal stabilizer is set properly in its slots.
edit - I re-read the post. Now I do think that it is warped. 80 degrees is OK for PBT but that is too hot for ABS, it doesn't melt into a blob at that temp, but it definitely starts getting wavy.
I have wrecked a number of ABS keys, attempting to dye them. My observation is that right around that temperature, where ABS starts getting soft, is very close to the absolute minimum temperature required to get RIT dye to take.
After washing keys, I drain them in a colander or wire basket for 5-10 minutes. Then I lay a T-shirt out on the bed, and shake the water out of the "cup" of each one, individually, and toss it down. If you get a good rhythm going, you can do it in a couple of minutes. After that, they are 98% dry in 10-20 minutes, completely in under an hour.