Huh, this is an interesting intercultural communiaction trap.

In my area, this is just used as a shorthand/slang/idiom for "nice, i respect that" or in place of a nod or "thank you"

Edit: i should add, that as far as i know, a chappeau is a type of cap or hat? Right? have to google that.

edit2: yes, a hat. The origin of the use I know for it is probably a salute where you touch your finger or hand to the hat, or lifting the hat.
Here saying "hat" seems to be enough :D