I use BirthdayType (for which parent DateType so the problem is the same).

->add('birthday', 'birthday', [
    'label' => 'my_custom.translation_message',
    'required' => true,
    'format' => 'dd MMMM yyyy',
//  'translation_domain' => false,
//  'choice_translation_domain' => false,
])

On Symfony 2.7.3 I get gazillion (more than 100) missing message warnings.

If I uncomment choice_translation_domain – the option is not recognized.

If I uncomment translation_domain – the warnings disappear, but my label does not get translated.

I believe, DateType and BirthdayType should have choice_translation_domain so that label does get translated while there would not be warnings for each year in the widget (ChoiceType).