Definitely not the sort of outcome you'd expect from Kentucky but I'd urge caution by not looking into a poll too much, especially after 2016 and given how highly charged the current climate is. A better gauge will be in a few months time.
Rather than being a Democratic surge, I feel he has likely lost some support in the eyes of many Republicans by failing to address the current issue the way many Republicans would have liked. As we get closer to election night though I'd expect those feelings will evaporate and turn into support at the ballot box.
RE: SHOCK: Mitch McConnell LOSING in Kentucky Poll