I just picked up my second M-A1 and I think there is something wrong with it. While the slide is racked back and there is an empty magazine in the mag well, I pull back on the slide a little and press the slide release lever down and it doesn't return to battery. I have to eject the mag and then it will. It does it with both of the magazines it came with. My other M-A1 will return to battery when there is an empty mag in the gun. Is this a problem? I ordered it from CDNN and they have a 3 day return policy so I kind of need to know if this is a defect pretty fast. Thanks.