Rear brake caliper bleeder leaks after I bled brakes on 04 Grand Prix, it is tight but now leaks.

Sounds like some debris in the caliper has lodged between the bleeder and the seat which is now allowing fluid to escape. Take the bleeder right out, clean it and examine it for damage. Carefully clean the port where the bleeder goes in, then have a helper slowly depress the brake pedal like you would when bleeding the brakes. Hopefully that will flush out any debris that is in there. Before releasing the pedal reinstall the bleeder, then pump again and see if it still leaks. If it does then a new bleeder or perhaps a new caliper is in order. They're not that expensive, so don't spend too much time trying to fix it.