Yeah, if found the same thing with my old Bayres.
It really bothere me, and I couldn't get all the air out despite several clever attempts. For a while I just left it, but the aire bubbles were driving me crazy, because I felt that they could possiby get sucked into the circuit.
In the end I used a piece of tubing, and a barbed fitting to make an "extension" of the reservoir, and bled it that way. When you are doing that though, you are basically making a Tee-line with the Rez as the Tee, kinda pointless. My new Rez is a cannister shape, which also has air trapped in it - but the air is way up at the top where there is *no* chance of it getting pulled into circuit, as the outtake nozzle is at the very bottom.
I would just try to ignor it if I were you, it is unlikely that it will cause any problems.