1. Could have a loose screw, body screws have to be tight or leaks will spring.
2. You could have a little grease on the derlen part of the poppet, this will cause a poppet leak.
3. Check all orings in the vicinity of the leak.
4. Check the manifold (little black rubber piece on the noid) - if this have lube/dirt on it it will leak slightly and come out the top frame screw under the bolt.
5. Go through all these steps, lightly grease the needed areas, put your gun back together, gas it up. If this doesn't work send it to BL.
i know it looks like youve solved the problem, but after i regrease my poppet and body have orings it takes a couple of dry fires to seat everything correctly and seal up tight. after a fresh coat of lube i would try the same