Its pretty normal. The weight from the flowers get to be too much so when rain and wind arrive, the flowers just get knocked over. My advice would be to cut the spent flowers off and allow new growth to occur. Most that have already fallen over will not stand back up. They will a little after a pruning but not by much. It happens all the time.

Next time, prune back the flower heads right as the stems start to bend. This will cut back on the weight on the stems. Hope this helps!

Thank you for that info. Would I prune the stems now, early July, and expect new growth to happen?