You're going to cry the day when you try to clone your Elastic Beanstalk environment to do a rolling upgrade, and the termination of the first wipes away your RDS db with it.
It's undocumented, but you'd be better off creating the db separately, not within the beanstalk wizard, to avoid this
Take one of your RDS daily snapshots (which you're taking of course), and recreate a new instance from it. Point your app to it, and you should be good.
It's undocumented, but you'd be better off creating the db separately, not within the beanstalk wizard, to avoid this