Trying to keep this brief: I report to two managers, A and B. I meet infrequently with A (~1x/month) and my day to day work has no impact on her ability to do her job. I work very closely with B and talk to him every day.
I asked A for permission to work remotely for two weeks. She told me it was fine if B approved. B told me it was not a problem at all. I brought it up in a meeting with both of them at once and it appeared that everyone was on the same page.
A month later, I mentioned in passing to A that I was leaving soon to work remotely. She had forgotten our earlier discussions, and became very frustrated that I had made plans without consulting her. She went on to tell me that it showed a basic lack of professionalism to do what I had done, but that it was common for new hires like me to "lack the emotional maturity" to manage their time effectively.
I was very confused by her reaction and I mostly locked up during the conversation. I assumed that I must not have actually told her my plans. I tried to explain that B, who I work with every day, reassured me it was a totally routine thing at the company so I didn't understand why it would be such a big deal. She told me that it was against policy for me to work remotely.
After our meeting, she emailed me to say that it turned out no formal policy existed, but she had worked other managers related to her position to create one. (Because of strangeness with the way I am managed, this policy basically only applies to me and a handful of other people across the company.)
I confirmed with B later that yes, I had mentioned it in a meeting with both him and A and that A said it was fine pending his approval. I had 100% followed the correct protocol and okayed it with multiple other people on my team whose work would be affected by my absence. It never occurred to me that I would need to make a bigger deal of it to A, since everybody I talked to --- including her, twice --- was extremely nonchalant about it.
I cancelled my plans to work remotely. Obviously, misunderstandings happen. I'm sure I was not as clear as I could have been when I discussed it with her. My work is very important to me and I'm not at all bothered by changing my plans... but I am extremely offended by the level of vitriol she responded with because of a misunderstanding on both of our sides. Even if I had made plans without consulting her, I feel like it was totally inappropriate for her to comment on the "emotional maturity" of one of her employees.
Is it best for me to just bite my tongue, or should I try to talk with A to resolve: (1) the offense I entirely accidentally caused her and (2) what I feel was a personal attack that she gave me in response? Do I write this off as a loss and just never bring it up again, or try to clear the air? I continue to report to her for about 4 more months, after which I will report only to B.