Short running times is a leading cause of condesation. Especially in colder weather. Just because the temp gauge reads that the temp is up means that the coolant temp is up to normal. the oil and engine components may still be only luke warm and not warm enough long enough to evaporate the water out of the oil. They should be driven long enough to bring all temps up to operating temperature and long enough to evaporate the water out. Condensation in a natural occurance in any internal cumbustion engine.