This is normal and it's due to surface tension. All overhead showers (and hand showers etc) will always hold water the bigger the size the more it holds no matter the make or model. If you have just used it on the top shower then move to the hand shower the odd drip will come out gradually getting colder as it cools. If you use the hand shower and the overhead hasn't been used since the last shower then it will be as cold as the room! Usually gets you down the neck! On occasion as the surface tension of water breaks, you may find it will "dump" the full complement of the head hours after use. No way to stop this as it's a natural law. For more info, you can Google it but it's boring!! How to stop it? Break the tension yourself, when you shower, on finishing tap the shower head and lots of water will come out. Next time you use the shower it won't do this. You can apply the same to a hand shower head, just leave it pointing down to drain