As is typical around here, we seem to get a secondary flush on many of our alpines come late September through October. Here are some current bloomers: Hypericum olympicum, Sedum middendorffianum 'Striatum', Pulsatilla pratensis 'Nigricans', Lindolofia longifolia and Papaver radicatum.
It is not uncommon here either. Plants (and animals too) have a tendency to behave springlike when the days become shorter in fall.
In my garden the dandelions have a second flush!