You open the App Center App and authenticate. You move the App Center App to the background. When you bring the app back to the foreground, the App Center App prompts you again for credentials.
This issue occurs for users running the App Center App on iOS 7 and authenticating through SAML.
The App Center App was crashing on minimize and was, therefore, prompting for credentials on a fresh launch.
This issue is resolved with 4.1.18; however, you will need to rebuild and redeploy the App Center App for the fix to be applied.
Rebuilding an App Center App updates the app to include any new functionality distributed with an upgrade. You must follow the same procedure to rebuild the app as you do to initially build it. After you rebuild the app, end users who use the App Center App are notified that a newer version is available to download.