Oh yeah, even the cheap-ish straighteners get really hot. I've burnt inbetween my fingers many times cause I absent mindedly run my fingers through my hair after I've straightened a section of hair.
It hurts, but its never burnt me seriously!
Dinos right about the moisture making your hair go curly/wavy. It happens to me and it drives me mad cause it takes me a while to get my hair poker straight :\