Apple has determined that, in a limited number of 13-inch MacBook Pro (non-Touch Bar) units, a component may fail causing the built-in battery to expand.

This is not a safety issue and Apple will replace eligible batteries, free of charge.

Affected units were manufactured between October 2016 and October 2017 and eligibility is determined by the product serial number.

Your 13-inch MacBook Pro will be examined prior to any service to verify that it is eligible for this program and in working order. Service may take 3-5 days.

If you believe your 13-inch MacBook Pro was affected by this issue, and you paid to replace your battery, you can contact Apple about a refund.

The program covers affected MacBook Pro models for 5 years after the first retail sale of the unit.

Note: If your 13-inch MacBook Pro has any damage which impairs the replacement of the battery, that issue will need to be resolved prior to the battery replacement. In some cases, there may be a cost associated with the repair.

More info and serial number checker for eligibility here.

Source: Apple Inc.