If you play on 1.7.4 (i do) heads look normal & fine. As soon i go to 1.8 i see skulls & steve's.
EDIT: I BELIEVE i see skulls. I don't really remember since i only played on 1.8 the day it came out. But I think the should switch back to what you originally saw them as if you play on a earlier version. But to someone on 1.8 they look different