Six, I'm thinking it's one of those things. Either sounds completely plausible because I generally just toss it in my pocket and I usually drip at HV so the juice gets particularly hot. This doesn't happen when I use cartos, just dripping. I'm thinking it's the latter. And yeah, sorry I didn't explain myself very well; it was 3 in the morning and it kept happening and I was tired and cranky and out of it. I can probably include that I never actually find solids in my mouth after that... it's really just the sensation, so I'm pretty sure hot juice is the culprit.
EDIT: Doomed, yeah, that is what she said. Totally aware. And I brush my teeth just fine, thanks!

It was definitely stuff coming directly from the PV, and doesn't have any correlation to meal times. I'm actually a little obsessive about tooth brushing, so I'm almost positive that's not it. Thinking hot juice.