I have similar loogey issues. It usually hits right after I eat. Starts with needing to clear the throat and ends with a massive hawker. I have noticed since being primal for almost 2 years, that I only get it now when I eat and extra saucy/spicy meal. Dry salad or meat doesn't provoke this response, but anything covered in sauce does. Sauces in this context can be anything from butter to olive oil or CO oil. However, the worst phlegm build-up occurs after getting a non-primal sauce like you'd find at an oriental restaurant with soy sauce, MSG, or corn starch.
I'd love to know the root cause of this also. I do think it is somewhat normal if it only occurs after eating and goes away after expelling the projectile. It's almost like overactive phlegm production or something.