Color cast issu in Ektar 4X5

[middlegray]

Any guess what may cause this color cast along the edge and on the right side of the attached image? I am suspecting this is a developing error and not any kind of light leak, just need second opinion. Thank you!

 

[BMbikerider]

There is fogging on the top right corner so I suspect that stray light has penetrated down the sheet. is the darkslide completely light proof?