Accidentally hit a pigman at my nether fortress. Traveled around 400 blocks away back to spawn portal, the pigmen there were angry as well. Had an alternate account go in and attack the pigmen, they ignored the alternate account and still focused on the primary account. Once all were dead, I left the nether and reentered. Pigmen did not appear hostile. Traveled to fortress, they were still hostile over there. Returned to spawn portal, pigmen were hostile again. Traveled over 1000 blocks away in the nether and returned, the pigmen by the spawn portal were neutral again. Logged out and logged back in, they returned to being hostile.