Honestly, it can be very random as to whether their spin is counted as a Level 4 or not. They have pretty much performed the same exact spin the entire season and have gotten all different kinds of levels for it (from 2 to 4). I think when it comes down to it, the technical panel may not consider the entry or the exit of the spin "difficult". I would consider it difficult to start a spin from no speed (for Hubbell) and to have an interesting exit with that three-turn hold, but that might not be considered "difficult" either. Their last spin position may not count as being difficult either - Hubbell may be in a layback-like position but it may not count as difficult.
Either way, I think H&D need to rework that spin so that the levels are far more clearer as being difficult, whether if that means changing the entry or going back to a spin from a prior program.