Hi Luc,
yeah your answer makes sense. On the other hand one could also argue that there are exchanges where the bulk of trade volume are handled and others with a limited amount of trade volumen. I dont know for sure but my feeling is that the exchanges with the major trade volume are bitfinex, Bitstamp and Coinbase to some extend.

In addition, Bittrex "only" trades the Tether version of BTC/USD pair and not "real" Dollars. So USDT is not always exactly wort 1 real USD. So one could also very well reason that what you said might hold true if the occurrance was on one of the exchange mit major trade volume and might not hold true if the price movement was recorded on another less exchange with less trade volume.

Probably time will tell if it was a gap that still needed to be filled or if the little appatizer it had was enough to be a satisfied gap.

Keep up the great work and thank you for you elaborate answer!