This liquid always seems to develop in the capitulum (seed head) or "bud" after flowering. It seems to be part of the plants normal process and is quite natural. At a guess, it might be over active nectaries continuing to produce nectar to excess but don't quote me on this. I have never had the urge to see if it tastes sweet!

do you mean the buds before they open or as fractal suggests the spent flower. mine do that after flowering too. but i dont know why. and i have never tasted them to see if they are sweet.