Reading these comments really shows that y'all don't know what mansplaining is (although, OP likely does cuz he knows what it isn't).
Mansplaining is not simply a man speaking condescendingly to a woman. It is a man explaining a thing to a woman that she already knows. The origin of this term comes from an essay titled "Men Explain Things to Me", which recounts an interaction that writer Rebecca Solnit had with a guy who read the book that she wrote and he explained to her the meaning of the book implying that her interpretation of what the book was trying to say was wrong, despite her having written that book. It has since been broadened to the context where men explain women's problems to them, despite women knowing their own problems far better often from firsthand experience. Is it condescending? Sometimes, but condescension is not always the intent or delivery of the man mansplaining.
Seriously, commenters, research a term before you argue whether it exists.
In OP's case, you were right to recognize that you weren't mansplaining and definitely dodged a bullet.