When playing in the nether, I will see Ghasts screech and look angry, like they are about to fire, but then not shoot. They then fly around like that until they despawn or die. This does not happen all the time, I'd say about 50-50. I know at least one other person has this issue. For reference, they have the same Android and Minecraft version as me. I just started noticing this in 1.6 and 1.6.1.