Seems a little shady to me... Either there was some "test" trading earlier or the graph is just combination of two unrelated trading pairs due to error in integration. In worst case scenario, Hive was actually listed earlier, but got unlisted due to lack of trading volume.

I've seen exchanges listing cryptocurrencies without contacting the team behind the cryptocurrency. Due to that there won't be any active promoting which eventually results in trading volume crashing after first few days when small group of people that were actually behind the listing request get bored filling their own orders...