I just wrote about distance on another thread, so I'm with Jackster there.
Also reading this I am now also wondering about the needle seat. If it's not situated properly paint could collect in the nozzle, and so when you pull back more paint os coming out than you would expect. Also are you getting any bubbles in the cup? There is the possibility that the nozzle is damaged or flared. Damage should show under a magnifying glass, flaring is harder to spot but you may be able to compare how far your needle sticks out with a photo. It os probably also worth soaking your nozzle for a while on some 4012, then taking a small paint brush with long enough bristles, and use it to poke around in there a bit, then back in the 4012, and repeat as necessary. When you reassemble, gently move the needle by hand to male sure its not sticky, spongy or gritty feeling. May as well eliminate all possibilities.
Also is this happening with more than one colour?