Why is there a watery run-off after cooking my bolognese? It's a fairly standard recipe with passata and wine, simmering on a low heat for a couple of hours.  After stirring and putting the bolognese onto the pasta, after a couple of minutes the sauce separates a watery run off onto the bottom of the plate.  The pasta is fully drained, and the bolognese seems good in the pot.  How can I reduce the wateryness, simply cook the bolognese for much longer?  I haven't wanted to risk drying it out/burning.
A few things that can help, if it's not an issue with fat like @Aaronut suggested:


Tomato paste.  Yes, I know it's a sacrelige, but it'll act as a thickener.
Take the pasta out before it's gotten to al dente, and finish cooking it in the sauce; the pasta will absorb any extra liquid, and help to thicken the sauce.
Do not rinse off the pasta after you drain it.  Way too many people do, and it washes off the starch that you want for the sauce to bind to the pasta properly, and may introduce extra water.