I think that this is a common problem in some plants ,which have been forced into an early bloom for Easter/Mother's Day .
Sometimes plants get too much of a shock from the change of being in a greenhouse then a shop then home .
But it looks like Botrytis ,which can affect roses and other plants .
Sterilise scissors or secateurs in 10 % bleach and cut the affected blooms /leaves right off and dispose completely and not in your compost bin .
Wash your hands and resterilise your scissors /secateurs .
I've planted mine outside in peat free compost with a slow release fertiliser .
I rescued my neighbour's miniatures last year and they are blooming nicely now .
If it isn't Botrytis - the pruning and replanting will be a little tonic and they will recover anyway .
Good luck and happy gardening .