Appreciate the response, and think you're probably right. I'd be interested in better numbers, though. It's not the mass of the ice cream that't the problem, but the fuel necessary to get that mass to orbit. I think that's about 10x. And it's the percentage of weight at altitude that matters, since that's where the maneuvering was being done, which brings the weight down by about 90%. That's why I was guessing it was a .1% increase, but don't know for sure.
For the ride up, SpaceX stashed chocolate-vanilla swirl ice cream inside.
the amount of liquid oxygen "was only enough to achieve a roughly 95 percent likelihood of completing the second burn..."
882 pounds (400 kg) of cargo aboard the Dragon capsule
The cynic in my wonders: would they have calculated a 99% likelihood if they hadn't sent the ice cream and had about .1% less cargo?