Well, she described it as a chant, so a prayer does seem likely. But again, this is a person who mocks religious practices and has traveled extensively and isn't freaked out by languages.

The fact that it was a burial site or crypt makes me think the setting was key to that response. Maybe movies or something predisposed her to be freaked out in that setting. Her theory was that the burial site itself was chosen for geographic features that made it make people feel freaky. I'm not sure if that makes sense either, but it's interesting considering how people try to explain unusual things to themselves.

It's perfectly normal to be scared in a horror movie even though you know it is fiction. Even for atheists. Human beings have wonderful imaginations; getting spooked by a creepy underground crypt shouldn't send anyone looking for a supernatural cause (or capture an $N million dollar grant).