Whilst I totally agree that the teacher should have spoken to you in private about this, giving you reasons for her concern etc, maybe you should follow it up , just for your own satisfaction if for nothing else.
What's the downside in having a Speech Therapy assessment (if you can get one) ?
If it turns out that there's no problem, that's fine. If it turns out that the teacher is correct (sounds unlikely, but who knows), you've taken the opportunity to have any problems sorted out at an early stage.
If you still have a health visitor, and they certainly used to follow up children until they were aged 5, she/he will be able to do a referral for you. Give the H V a ring and explain what has happened, or speak to the GP at the hearing test.
All the best, I'm sure all will be well .
Some teachers just forget that they're not always dealing with small children...