No its not odd at all.
You said that coffee dehydrates the body. The water doesn't just disappear, it has to leave the body some how. So it either has to make you sweat more or pee more or it makes you vomit or have horrible diarrhea.
yes it is,
one cup off coffee shouldnt make you pee 7 times "at least not in larger quantaties" it's in the way that coffee dehydrates the body. they are only slight dehydrates in them selves, whats worse is that it dosent replenish the body and therefor you over time dehydrate "at a preaty normal rate" yet by drinking coffee, cola, tea, "beer" ect you fool your body into thinking it's getting what it needs.