Ok. Good to know. I don't always restrict the air and when I do, it happens for the first 2-3 secs of a 12-15 sec draw. That said, if it wasn't meant to be restricted in any way and especially since the Milaana works perfectly fine without restriction, I'll probably refrain from doing it moving forward. I'm definitely very new to the RBT vapes. This forum has been really helpful and I do appreciate that.