Hey man using a clone taken from a flowering plant can cause problems. The cutting has to return to the vegetive cycle before it will start to root - and when they take 7 - 10 days to root normally ie. when they have been taken from a plant already in the vegative state; the extra time to turn back is often too long for the clone and can result in malnutritioned plants with poor root systems. It can be done but if the situation permits I would always take my cuts from plants in the vegative stage. Hope this helps.
Digitalphd