She doesn’t want to be found out as a saint, so she doesn’t want anyone to figure out, that the reason behind her extra power is “that”.To begin with she didn’t know what was normal, so it was unavoidable, when she first accidentally gave them “the hint” (but she managed dodge the bullet, by saying that’s probably cuz she’s from another world). After that, whenever she accidentally slips a hint (when she comes across new things that she’s more powerful at), she gets somewhat irked, as she SOO wanted to hide it!
That’s why out of irritation, she calls it a curse, she doesn’t really hate it.(she just hates inadvertently showing it)