1) Plenty of good advice above about keeping an eye on her. especially possibility of a prolapse after pulling the calf.
2) If the heifer was bred or AI'ed to the same bull as all of your other heifers, but she is the only one that threw a big calf, might consider sending her down the road. Given that birth weight and calving ease tend to be genetic, if she was the only outlier.. "Here's your sign..."
Good luck with which ever option you choose...
