Concerned about shaking orgasms

I do not know if it’s an issue but my gf 19(f) has such strong orgasm that they look like seizures to me. She doesn’t have is not very experienced and we have probably done it like 20 times so we are not sure yet if this is normal. To me it sometimes looks like she is not okay even though she says is. She is not able to respond to me for let’s say like 30 seconds to minute and I het really worried, because it does not look like something a person’s body should do during orgasm. It looks like her whole body starts shaking she is breathing heavily and sometimes she speaks gibberish afterwards. I even think there was one time when she couldn’t remember where she was. Should I be worried or is this normal?