I actually had a very similar experience once related to the day (rather than time) and a Domme who was originally from Eastern Europe. I was in town with friends and told her I couldn't come until 1am (which was actually more acceptable to her than 1pm).

The problem was that 1am is technically the next day and there was confusion about Friday night/Saturday morning (which is what I meant) vs Saturday night/Sunday morning (which is what she thought). So, when I called to confirm on Friday at 11pm, she was like "WTF?".

She had her own private dungeon and no conflicts so she was easily able to adjust her plans to actually meet at 2am, but I did take what I consider to be an undeserved punishment for it (I still feel I was clear and the fact that English is a 2nd or 3rd language for her led to the misunderstanding more than me not communicating... but, the Domme is always right in these circumstances). Now, when I need to do something later at night with her, I try for 11:59pm or use the double date convention I did in the previous paragraph.