He may not have remembered her, but Semele certainly remembered him. Perhaps it was because she had less mythology to hold onto than him. But she remembered being plucked from Hades by him, remembered being brought to Olympus and being made the goddess of frenzy, remembered standing strong by his side as she mocked Hera's failures to destroy her, remembered dancing in groves and leading his wild maenads.
She made a face as his words, "'Mother' makes me sound so... matronly. Let's not go with mother."