It isn't something you could call a fatal mistake, but better avoid it. Jumping backwards can cause a disbalance that will be significat issue, and sometimes the jump backwards itself happens to be the fix of another form of disbalance generated during the initial pull itself. Do you have a coach who keeps an eye on you?
I've seen people who do it intentionally, and others struggle bad doing it. Even elites sometimes happens to do it in a lift, and in the next attempt they don't.
Here is a case: https://www.youtube.com/watch?v=eVTMUEYhwDE
Now, in your next attempts try to "jump" upwards, and land on your feet slightly spreaded, i.e the movement on your feet to be to the sides (a shoe width more in each side, toes slightly out), and while getting up, bring them back closer to the position they were right before the initial pull.
Take a look at this: https://www.youtube.com/watch?v=nLNzd_FcThs - Check out the first two attempts in this video. In both, and especially in the first one, you'll see an attempt that can be used even for research purporses. Check it out.
As for cleans tomorrow, rise the weight up a bit, so it will be easier to spot issues and mistakes, but be reasonable with the numbers.