From what I've found in my research in the last 2 days (just found out yesterday that my own case was sent to "review" last week) I think it's okay for you to stop feeling pukey over this.
It's
highly more likely that any case sent to review is an approval rather than a denial.
The info I just found out is that at least 50% of all approvals must be sent to review. That's in contrast to a mere 70 denials per branch per quarter that are randomly selected for Quality Review. The other good news is that less than 2% of approvals are reversed during the review.
So, given the odds, I think it's okay to look for that letter with a healthy dose of optimism. Just keep a tiny little portion of your sanity ready for a just-in-case contingency plan, but it really is an outside chance that you're looking at a denial.