Guess we've answered that question about if Beto will ever lead in a poll.
As others have said, it's probably not the best poll, but it's a good sign.
This was my first thought as well.
But how credible is the pollster? I never heard of this particular firm.
As others have said, they are a new venture created by the same people that fund Daily Kos. (This doesn't necessarily mean they have a bias; Fox News is biased, but their polling is quite good.) They have no rating from 538 because they don't yet have a track record to measure, but they do have some good people (e.g. Drew Linzer).