I think you're probably right about that.
It may even show itself in the next three episodes as a result of coping with some sort of tragedy.
It's like a ticking time bomb waiting to go off.
I keep remembering Daryl's squaring off with Bob during S4E4 about his drinking and no supplies in his bag but a bottle of booze and what he would do to Bob if his alcohol caused someone to die.
Who knows? Maybe he will clean himself up.
It wouldn't be as good television though if something horrible didn't go down first.
That's not meant to sound like I have a bit of schadenfreude