Welcome Alfredo :)
TL;DR
No. Android apps are "sand-boxed" inside their own user in the operation system. So unless Snapchat/you Android version have a specific vulnerability (and if you update your phone this shouldn't happen), other apps are not able to get stored passwords.
Application Sandbox in Android
Android is based on the Linux operation system. Thus, it isolates apps from each other and protects apps and the system from malicious apps. To do this, Android assigns a unique user ID to each Android application, which means all the application files, unless defined otherwise, are protected and accessible only to this specific application (user id).
Other mechanisms for saving users passwords
Android also implemented an account manager, in order for apps to save tokens and passwords securely. In short - that's an encrypted DB that is managed by the operation system itself, and every app could save tokens/passwords using it, in a secure manner.
