I have similar observation about the side panel. It's just because of the high number of cutouts for ventilation making the flexural rigiridy a bit lowr (especially towards the free edges that slot into the groove. It's not so much a problem near the back and bottom, where the bent flanges help out quite a bit with rigidity). I think this is a fair tradeoff in exchange for better ventilation (and so far my experience with this case has been very good regarding temperature)
If I may suggest an improvement for the next revision, it would be to add a second screw to mount the side panels from the bottom of the case, securing the panel onto the floor of the case. This should help the side panel settle into the groove a bit more securely at the top, near the curved edge of the faceplate (right now the panel is only held from one screw at the back, so if you are not careful when handling the case, it is possible to grab the case by the front part, and pulling the side panel down, away from the groove)
I think this could be accomplished without adding too much cost to the BOM (one extra hole or notch on the bottom flange of each side panel, and a corresponding set of two holes on the floor piece of the case, with threaded inserts)
If I may suggest an improvement for the next revision, it would be to add a second screw to mount the side panels from the bottom of the case, securing the panel onto the floor of the case. This should help the side panel settle into the groove a bit more securely at the top, near the curved edge of the faceplate (right now the panel is only held from one screw at the back, so if you are not careful when handling the case, it is possible to grab the case by the front part, and pulling the side panel down, away from the groove)
I think this could be accomplished without adding too much cost to the BOM (one extra hole or notch on the bottom flange of each side panel, and a corresponding set of two holes on the floor piece of the case, with threaded inserts)