This has happened to me more than once. For some reason, the Enchantress's skill Mass Control has sometimes caused me to become hexed. At first I thought maybe an enemy had hexed me, so I stayed silent.
Today, however, while fighting Frozen/Waller Dune Beasts in Act II Nightmare, I was hexed, along with some of my enemies. I did not see any other enemies than the dune beasts, so it seems like the only possible explanation is that sometimes the Enchantress is able to hex me as well?
Let me state again that this has happened to me before.