I went out earlier this week and shot my police trade-in 4586. It seemed to shoot fine, bit every few rounds, it would eject straight back, just over my head. When I got home and took it apart to clean, I noticed that the guide rod is slightly bent in thew middle. I know that a replacement is easy enough to obtain, but I'm wondering if there is something going on in the gun that could cause another bent rod, or if (probably more likely) it was dropped while the slide was locked back. Also, could the bent guide rod cause the screwy ejection?

I would expect the ejection to be more ammo; maybe the ejector or extractor.

Because of how the slide is held on the frame by the rails, I suspect the rod when bent either when out of the pistol or maybe if it wasn't held in place correctly when it was being reassembled.

The bent rod could cause interference between slide and recoil spring, resulting in erratic slide action. You could straighten it out by tapping it with a soft face hammer (rubber/plastic) and rolling it across a flat surface until the bow is gone.

Recoil springs have more to do with wild ejections than the rod. If you're ordering a new guide rod, I'd install a new recoil spring. They're cheap. Check Wolff Springs. They run about $15 + shp. Wolff usually supplies a firing pin spring also, but that's not something I'd try to change myself.