Not trying to be too simplistic, but if that happens again, loosen it with hot water and be very gentle and remove it with a shaved piece of wood like a toothpick or popscicle stick so as not to damage the glass, metal or o-ring. Plastics, including silicone, tend to be very sticky when they are new or shortly after full tactile cure. The stuck-ness could be simply from the o-ring being put in before it actually fully cured and degassed.
Just my guess. Of course if you have 100 of those babies, rip away.
Just my guess. Of course if you have 100 of those babies, rip away.