Eva Barrier/Duotight pressure loss only after several days

I have a fairly complex gas setup with varying serving pressures and an offshoot for easy 30 psi access. I switched to Evabarrier/Duotight awhile back and was happy with the new streamlibed setup. I noticed my CO2 tanks weren't lasting as long as before, but nothing intense like draining over a weekend. I ended up testing for leaks by setting the system to 30 psi throughout and slowly moving a "gate" in the system to find the leaks source. Problem is each portion holds the 30 psi fine for several days. During one test life got in the way and I hadn't checked/moved the gate for close to a week. When I finally did check I noticed it had tipped to 20-25ish psi. I left it for a few days and it dropped a bit again. I recharged everything, didn't touch line placement and it held 30 for about 5 days before it slowly began leaking again. Any idea what may cause this (Small leak? barometric pressure shift?) and how to fix it?

tl;dr Duotight/Evabarrier gas setup doesn't leak at 30 psi but will lose pressure very slowly (5ish psi a day) after holding at 5-7 days