Header flag not supporting periods

When attempting to set a customer header that included a period, i.e. consumer.id hey is returning the below error

could not parse the provided input; input = CONSUMER.ID: 1234

Based on the regex that is being utilized ^([\w-]+):\s*(.+) I don't see how it would be resolved and I'm not aware of a period being an invalid character based on the latest RFC. Is this expected behavior?