Not a bad play IMO if you are long and worried about air pockets.
I think the secular bull has a ways to go yet, but internals on this rally are weak and it seems like folks have been front-running year-end seasonality. Seems like more of the same pattern from the past couple years: VIX positioning creates a pattern of vertical upside rallies and subsequent drops, but moves lower likewise get V-reversed as passive flows, short squeezes and the Fed come into play.
2020 is going to see concern about a Warren presidency among the stock-owning class, and with that in mind it's not clear if/when the indices can manage a sustained breakout.