This is a typical flower on my ‘Temple Bells’.
It always has 7 petals. Does this mean it isn’t a true, genetic single (5 petals), but is really a double with a really low petal count? I’m curious because this is an OP seedling from it (first flower):
‘Temple Bells’ selfs pretty much before the flower even opens so the chances of the above seedling being an out-cross is remote. If double is qualitatively dominant to single this seedling makes sense.