Some of the Hesperantha bachmannii flowers seen in the Biedouw Valley in September had these pink-purple outer tepal surfaces, while most of them were white. It appears as if the coloured flowers are the older ones, the buds white.
Since H. bachmannii flowers only open in the afternoon, these may have been ones still to reopen for belated pollination events, if their inner components were still up to it (Manning, 2007; Leistner, (Ed.), 2000; Bond and Goldblatt, 1984; iNaturalist).