Yes, this has happened to me, and it never surprized me because nursing is a competitive field, filled with petty, jealous people who like to knit-pick. And, yes, they are the sloppiest ones, the ones that speak the loudest. Hard to say how to handle it, since I am a new nurse, myself. At the moment, I suggest to take it up only if those that can fire you approach you.
What I hate is when there is an employee, who has no idea what the job is in nursing tries to knitpick. An example of that is I had a patient who came in for a shot of testosterone. We work in a city hospital, where the patients can be seen whether they can pay or not. My responsibility is to check and see that the proper prescription is in, that the proper paper is stamped, that the script is not outdated and to adminster safely. A patient came to me with the proper papers that I needed to see, and I gave the injection. The desk person tells me that I have to check and see if the patient paid, and I told him that this particular portion is his job, and that he has to follow up about payment, not me. He then said that I don't know my job, and I corrected him by stating that I did mine, but I don't have to do his.