Not one of the symptoms you describe indicates any possibility of RI - I've been keeping snakes for over 50 years and all I can say is that snakes in my care have often exhibited the things you describe, and none were ill in any way. If the snake is behaving as it always has done - especially feeding (one of the first indicators of RI is lack of appetite), you have nothing to worry about. I would say that you have become over-sensitive in your observation of the animal, and are simply noticing things that have been there before, but your increased surveillance is causing you anxiety.
Just relax and enjoy your animal. There are many commentators here who freely offer advice without the experience to back their advice up. If you take the animal to a vet, it will not exhibit the head twitching you describe in a stressful situation like that, and in the absence of obvious symptoms such as noisy, rasping breathing, frequent, long-lasting mouth gaping, or mucus collection in mouth or nostrils, the vet will be just send you home with a clean bill of health for the snake, but $60-$100 lighter in the pocket.
Unless you see any real indication of disease, you are wasting you time and money. I repeat, NOTHING you describe indicates abnormal health in your snake at this stage.
Jamie
