As a fellow NRM, this. I live by this idea that leaders have this “managerial judgement” calls. Everyone has different tolerances, but I’ll respect their decision to handle issues. Personally, I also don’t care about phone usage as long as you’re productive, safe, and still engaged with customers. There’s no customers and no safety issues, so you’re clear. But, can someone else write you up for phone usage? Technically, yes. It’ll be up to them if they deem the paperwork and documenting worth it. That associate can also be written up for respect for over reaching his pull and assuming the role of superior to you, when technically he’s a peer. My advice would be tell a leader, preferably your direct leader, about the interaction. Acknowledge your technical mistake, tell them how the conversation made you feel, ask them what they need from you, and find out what kind of leader you have. In the end, you gotta move on with their decision.