Reproduction:
-Spawn/Find a baby pig.
-Approach the baby pig.
What should happen:
The baby pig should acknowledge the player by looking upwards.
What actually happens:
The baby pig does acknowledge the player, but doesn't look upward.
NOTE:
This has been tested with other baby mobs, and they do look upwards at the player.
I can confirm this issue. You can get the baby pig to look up slightly (especially when holding food), but it's not quite right.