This problem happens even in fresh installs without gapps (I tried it), so the problem is on the OS.
According to a guick google search, this problem was most likely NFC related. But I already had it disabled.
Seeing build 3 didn't fixed it and PA legacy community didn't pay attention, I switched back to CM11 but, to my surprise, the same wakelock was still there and my phone not sleeping.
Since it was a fresh install, I went to settings and disabled NFC. sns_eve_syn_wakelock was gone, but a new wakelock occupied it's place: Nfce:EemWakelock (or something like that, not sure), so I got confirmation that google was right, it was NFC.
So I proceeded to flash this http://forum.xda-developers.com/show....php?t=2544811.
Problem is fixed. My phone is deep sleeping again.
Of course, it's a TEMPORARY fix, until developers can find out what's wrong with android sources.