Definitely not a "print", nielsjust, otherwise it would look like the front.
But I like Johan's reference! I've asked about this in the past... Both the Ivory Heads and 64s are made with highly fugitive ink, so I wondered if a 64 could produce this kind of effect if the ink was fugitive *enough*.
Hard to tell with the 3c because it is a workhorse stamp, and there are plenty of variables that might cause it to bleed like that (varnish ink also does this).
However, I can't be certain from a screen, but the non-weathered areas do show signs of the "cotton candy" color found on a 64, especially in the top-left peroration:

If it were mine, I would submit it as a 64a and see what they say. Go all the way with it. Worst case scenario they'll label it a 65 and drop the expertizing fee... A little money might be wasted, but for me it would still be worth it.
*Edit* If the color looks way less saturated than the picture, take what I said with a grain of salt!