I've seen and experienced this too, and I think it's a couple things.
One, you're right, some long timers have so much of their self-esteem wrapped up in how many years they have of not drinking, that they are judgemental and self-righteous, sometimes because that's all they have.
But two, people in the early days of sobriety are often emotionally reactive and easily upset by things that other folks wouldn't pay much attention to, like that old-timer being self-righteous again.
It's a bit of both, in my experience, and the balance can seem to change was we build up long sober time ourselves, and become less likely to permit other people to control our emotions with their actions that we cannot control.
Originally Posted by
JWS 
For the most part, people in AA are awesome. No doubt, alcoholics are selfish people when intoxicated. In sobriety, alcoholics tend to do a 180 and become generous. I still can't help to get annoyed by the "holier than thou" crowd. Typically these are folks with 5+ years sobriety. They look down upon those of us who don't even have a year. They sometimes even ridicule when we share something they may not agree with. They monopolize meetings with their wisdom, yet lecture newcomers who talk greater than one minute.
I will continue to avoid alcohol. Once I prove myself and get 1 year, I am going to start seeking out the bullies and tell them where they can take their elitism.