Unfortunately there's no clean and easy way to move it since there was no indication in the prior version where the feedback had been posted.
What I could recommend is that if you're familiar with the table structure, maybe go through the entries and then assign them to the portal id that you want them to belong to. However this is a do it at your own risk :).
Having the feedback broken by portals was very important and lacking in the previous versions and I think that moving forward you'll see a lot of enhancements with this module which will take advantage of this fact.

Sanjay

Actually as soon as I hit reply, I realized that you could do this - same way you wrote in your post...
Thanks for quickly jumping on this. I'm going to pin this post so that everyone can see this as a way of updating their existing feedback posts till I can get it in the next release.

Sanjay