theres a gasket between the head and the casting (its the thermostat housing btw)
wouldnt do any harm at all to whip it off,replace the gasket, and perhaps the thermostat while youre at it, but mainly to clean up the thing. ive been mucking about with my coolant system lately and turned out the surface the hose comes in contact with had corroded and i wasnt getting a very good seal there, causing a slight drip. could be something similar with yours. i just wire brushed all the crap off with the housing in situ and it was fine.