Drying plastic bottles

[Sausages]

I cleaned a batch of bottles at the weekend and left them draining, inverted, in my drying rack. The glass ones are now dry and have been packed away, the plastic ones I use still have lots of small water drops inside that are not draining out. They're the brown Coopers PET bottles. Are there any tricks to getting them dry?
Or, conversely, should I worry about them being thoroughly dry before storing them? Might be a month before I have a brew ready to go back in them.

 

[Empty bottle]

I always rinse every bottle after use and leave them upside down on the dishes draining rack for a few minutes and then when i take them off the rack i hold the bottle upside down and use a whipping action repetitively like i am trying to throw the bottle into the ground vigorously and that clears any drops left in the inside. Put the cap back on and they are good to go for the next fill up. Just make sure to have a good grip doing this with glass bottles. Very easy to do and it works a treat.