Nendi's well aware of Faithe's track record regarding getting too big from her many funny stories and assumes she's generally okay with it, with her reaction towards Faithe's detonation being mild concern when it appears to be accidental, usually within the "Please be a little more careful, ok?" range of emotion. Nendi isn't too fond of popping herself unless she asks for it.
Faithe LOVES popping where applicable to herself. It's a quick way to get a lot of air out of you in a hurry (which isn't often), and lots of good adrenaline on top of that (even though it stings like hell). However, she's not too fond of it happening to Nendi unprompted for the very same reason (it stings like hell), usually falling in the "Oh my gosh, are you okay?" range of emotion should it happen.