At this point in time, despite intentions to the otherwise, BTC is primarily a speculative cryptocommodity. As such, difficulty will follow price, with a lag. Not the other way around. That lag may be months behind the price, not days or weeks. I think the difficulty is just now catching up with the influx of miners that came around (including me) in the rise up through $10-15 BTCs. We're nowhere near the difficulty we'd hit with a sustained $30.
I'm not sure I understand this. We're not exactly talking about the chicken or the egg argument. BTC difficulty clearly preceded price since bitcoin exchanges didn't even exist during the first difficulty period. Difficulty came first, followed by price a ways down the road after it.