HP 15C iPhone app blinking numbers

[Lammergeier]

[reposted from the HP support forum at the suggestion of a user there]

I recently got an iPhone 4s and bought the 15C app to complement my "hardcopy" 15C (purchased in 1983 and still going strong).

When I run a program on the app that is step-for-step identical to one on my calculator, it gives me blinking numbers when it's done. Am I doing something wrong or is this a known bug?