mine was leaking 2 days ago too, it was in my pocket without the battery so it could have tilted upside down or something, well it didnt really leak out, when i took it out of my pocket the juice was already at the tip of my drip tip.
i realize you need to somehow align the silicon piece on the coil head and the metal cap, mine doesn't really leak now but when i suck too hard, i still get some juice inside the drip tip, just have to use some tissue to clean it once in while.
Yes u got it right the top cap must sit properly on the rubber cap of the atomizer. If it does not than the rubber cap might got flatten a bit to create the gap.