I did this few weeks ago. All my feeds under my Feedburner account had been integrated with my Google Account. I managed some feeds, not only for my blogs, but also some other blogs I maintain. It’s encouraged to move Feedburner into your Google Account. When did this, I had no problem. Google has some details about this.
I just logged in to my Feedburner account and found something strange. Some feeds got no subscribers at all. Currently, I do not only manage feeds for my own blogs, but some other blogs. In total there are more than 30 feeds. I hope it’s only because a short maintenance.
Added later: It seems that everything is back to normal now.