Rotary cutters and fingers are NOT a good combination.
Fortunately, the fingertip in question is not as badly mutilated as I first thought, although my bathroom floor is still a biohazard (some blood dripped, but I'm not going to go slopping around with a mop and rags and stuff until this weekend.
The amazing thing is that I did not bleed all over the rest of the house or onto the fabric I was cutting. *smile*
No, no stitches - it's only about 1/4" long - just DEEP. Still hurts some, and bled like crazy on Sunday night when I did it.
Boys and girls - DO NOT try this at home!!