I think zghorner is on to something. Each post viewed in a vacuum, some people seem to get away with things others wouldn't. Viewed in the context of their entire post history, though, I think that people who generally behave themselves but occasionally cross the line tend to get some slack, whereas people who are continually pushing the limits and consistently antagonizing are more likely to get some pushback. I've been on both sides of that; when I used to be more of a jerk, I was more likely to get censured by the mods, and now that I'm a lot less of a jerk, I tend to be overlooked when I say something that's...impolite or inappropriate. Matter of fact, I've had a few that I've walked back before the mods called me on it.
I don't think that's a bad thing, either. We all have our moments, and we all deserve a little slack. It's when it goes from "our moments" to "irritating burr under the saddle" that we need to start looking at how to get the burr out of the way.
Because Dave said it so well, I'm going to echo it. Let this serve as a public reminder. If you're generally nice and helpful and respectful of others, it will take a pretty egregious error to get a warning. If you become rude / offensive / disrespectful in general, you absolutely become the "burr under the saddle," and we will start watching you very closely. I'll also say this, almost everyone who achieves burr status get complained about by upstanding members before we start tracking behavior. So it's also not just the mods that get irritated by that behavior.