Keep in mind that the aforementioned data does not forego a vet-check. Any sick animal, regardless of species, should be examined by a knowledgeable practicioner.
I would because what we think is the on set of an RI might be the precursor to something bigger or the RI might be worse than what you think. Its always a good idea to take your herp to a pro when its sicks they can better asses whats going on and what you think is an RI could be something as simple as a nose scale whistling or something as bad as cancer. I'm not trying to scare you I just want you to see that for any illness a vet is 99% of the time needed. The only time an experienced heper want take there snake to the vet is for minor injuries, stuck shed and so on.
It just me and if it were my snake I'd rather be safe than sorry.
Hope this helps -Ed