Can you see any signs of oil leaks anywhere? In particular looking under the front of the car:
- Alternator/oil filter mounting?
- Front face of sump?
- Exhaust heatshield?
- Front of block, behind exhaust manifold? (take heatshield off to see better)
Run your finger under the edge of the rocker cover, especially round the front left/front right corners to be certain this isn't leaking.
Did you replace the gasket yourself? We had one done by a dealer (no names...) that was - frankly - a balls-up! The lower face of the gasket is ribbed to make a good seal against the head face, but they'd slathered silicone sealant into the grooves so it was flat-faced an was never going to make a good seal...
...oh, and at least two of the retaining bolts weren't torqued down properly. One was only finger-tight (front left - as you're looking at the car) and the long bolt immediately behind that, next to the cambelt cover, had been inserted at such an angle that it missed the threaded hole completely and was just pushed into a recess in the head!!!!!!
If you are absolutely sure it isn't the gasket it could be the exhaust manifold studs. These are very close to an oilway and - especially on recon heads - the stud can break into this.
It isn't disastrous however and can be sorted by removing the studs, cleaning thoroughly (and the threaded holes) then applying high temp threadlock sealant before refitting them.