Issue
You are wondering if there is a maintenance history for your Heroku Postgres database.
Resolution
You can view the most recent maintenance history for your database with the heroku data:maintenances:history command. Heroku also sends an email before every maintenance event that you can search for. Before running the command, it is required to install the Data Maintenance CLI plugin. Dev Center article for reference: https://devcenter.heroku.com/articles/data-maintenance-cli-commands