Flower deformation

 This flower of HAMBLEDON shows characteristics common to a small patch of my bulbs that I share with another grower.  His flowers are similarly affected.  Many flowers are starry, small and wavy in the perianth.  Foliage is normal. Some varieties are unaffected.  Damage has occurred across one, two and three year plantings.  My guess is that this year something happened at flower initiation but I’m stumped as to what it might be.  Seems unlikely to be spray damage as the foliage is fine. I have lifted a few bulbs and they are firm.  Last year’s flowers were excellent.  Comments and thoughts are appreciated.   Michael