More info and video: it seems to be related to either height or pathfinding. Endermen ignored my gaze when I was above them. I made a sand pillar so I could go down gradually. They continued to ignore me until I was 4 blocks above the ground, then when I looked at one, he attacked me. I recorded a short video of this: http://youtu.be/AdfAUPGkV-o
Ha, no. Survival. No mods. Normal difficulty. Other mobs were attacking me.
Just had this happen in 14w11b in my survival world. Was sitting on a horse with diamond armor, looking at a map in my hand. Really upset to lose my best horse and the armor! Are there any tools I can use to get them back?