My orthodontist said that i have an unusually high palate. is that something that's bad?

Not bad: The high palate often narrows the palate. The orthodontist will usually try to widen the palate if the high palate affects how the teeth fit together.

15%: 15% of the patients i see have a high narrowalatal vault requiring palatal expansion. I'm pleased your orthodontist has recognized this as a problem for you that requires treatment. Trust him/her.

No: I high palate is a normal variation of human anatomy.

Not bad - important: That observation fits into the constellation of information your orthodontist uses to diagnose and treatment plan your case. If it presents relevance to your treatment, expect a discussion about it but it isn't inherently bad.

Airway problems: The narrower maxillary arch and higher palatal vault leads to airway problems and potential OSAS. The good news is a narrow palate can be corrected by orthodontic treatment. Good luck.