A green cast is usually more likely to come from scanning or inversion than from shutter-speed/exposure settings. C-41 color negative film has an orange mask, so if the scan is simply inverted without proper film-profile correction and white/color balancing, the result can look green or otherwise strongly tinted.

Try correcting the scan first: use software or scanner settings meant for color negatives, compensate for the film base color, and adjust tint toward magenta if needed. If the negatives themselves look normal and only the digital files look green, scanning is the likely cause.

A green cast can also happen with old film or film that was stored hot, but that’s a film condition issue rather than a camera setting problem. In short: your development may be fine, and your shutter speed would not normally cause an overall green tint.