Is she sick?...

I have 1500+ female pastel that has just entered her pre-lay shed. Yesterday i checked her mouth(i do this to all my snakes at least every month or so) and it looked perfectly fine except there were bubbles in her mouth... They were very small and didnt look like snot bubbles just tiny spit bubbles.. Im just a little concerned because I know that bubbles in the mouth could mean RI. She has not been wheezing, sniffling, or blowing bubbles from her nose, and she has been acting normal. She hasnt eaten in about a month, but just accepted a large rat this week.
Im pretty sure shes okay, I just want other peoples opinions on why this might be.

**Her temps and humidity are ideal**

Thank you in advance :)

I would just keep a close eye on her. Like you said it could be a sign of an RI starting, but it may be nothing.....

Maybe bump the temp slightly and keep an eye on her.

I notice this and some water dripping out sometimes after my ball pythons take a drink.. So do keep an eye on it if it persists, gets any worse, or shows any other signs of RI then I would consider RI. Meanwhile, like the rest have said, bump up the temps and maybe humidity.