Happened to me too once before, really surprises you when it happens though I didn't have time to check if there were any blips on the scanner when it happened to me.
By the looks (hard to say as the clip is so small) but you did receive a message in local chat, perhaps from npc[?] just before you jumped. May be the reason. I've heard some cmdrs suggesting they've dragged an npc to another system whilst in the interdiction mini-game and you happen to cross and align with the escape vector/destination so the countdown can start, this bug you've shown is probably similar in some way.