Stevens 320 Ejector Issue

I bought the Stevens 320 Security model (18.5" barrel) from Academy last month. Mine came already equipped with a heat shield and ghost ring sights. The first time bringing the gun to the range, I put about 50 of the Federal Target Load (2 3/4" 7.5 shot) down range. Towards the last 15 shells, the shells stopped ejecting properly and only partially came out. I had to flick them to get them out completely. After doing some research and taking the gun apart myself, I found that there was no ejector pin and the ejector retainer was slightly bent. I ordered a new pin and retainer from someone off of Ebay and was able to replace them correctly. So far it's been doing amazing. I've put another 100+ rounds through the gun, some being the same Federal Target Load and others being Winchester ( 2 3/4" 8 shot). The only other issue I've had after replacing the parts is that I had two shells eject at once. I'm not sure what caused that, I'd assume it was my error.