Fuschia Blooms dropping off

I have a beautiful Fuschia in a hanging basket which has been so prolific with masses of very healthy looking blooms and its still going strong. However there is one thing that is confusing me. Every day perfectly healthy blooms are falling off probably about 6 or 7 of them. Obviously along with them there are blooms that have naturally died. It doesnt effect the overall effect of the plant because there are so many blooms overall but I cant understand why this is happening. Is it ususal? The blooms are bright, healthy, new and stiff not floppy and old. I water and feed regularly so lack of water cant be the problem. The only thing I can think is green fly. It seems to attract quite a few and unless I regularly spray, like every other day, it could get out of control. Because of the frequency of spraying I use rose clear perhaps once every 6 weeks and the rest of the time fairy liquid mixed with water.
Can anyone explain this problem or am I worrying unnecessarily.