Thanks for the input.
So as it turns out, Newmar parts does have the replacement item. I was unable to find it, but once Newmar provided a part number I was able to.
I just double checked the condition of the spline before ordering a replacement and what I noticed was that the spline looks okay. But I did notice that the edge of the glass was about even with the edge of the frame, so there was no glass in the frame for the spline to grab onto.
I proceeded to pull the spline out on the other edge of the glass and probed for the edge of the glass. I was able to probe about 1" and still did not feel the edge of the glass. So apparently the glass has shifted and is no longer centered in the opening created by the frame.
This brings up another one of my issues, which is most likely the reason for the glass to have shifted. The shower door has two magnet that hold the door closed. These magnets are too strong such that you need to pull the door pretty hard to open it. When this happens the frame that has the magnets are attached to it bows. This pulls the frame away from the shower and has had the effect of pushing the glass towards the outside wall when the magnetic pull is broken and the frame straightens back up.
So what I need to do is somehow ease the magnetic attraction (new weaker magnets?) and then recenter the fixed glass panel. Once the panel is recenter, I suspect the spline will stay secured.