Considering that there were less than twenty girls of Hermione's age at Hogwarts when Lupin made that statement, I don't think Hermione should let her ego get *too* inflated. It's not like being top of your class at MIT. I love Hermione. She's certainly my favorite of the Trio, but that's not a high bar.
In a school full of pubescent girls, each one learning how to deal with her own 28-day cycle, and Hermione is the ONLY one to figure it out? I doubt that!
Besides, if werewolves are a known fact, not a legend, the disease can't be that hard to spot. I'm sure all of Ravenclaw got it, including the boys, and any Hufflepuff boys who didn't figure it out on their own were told by their housemates.