I would HIGHLY recommend getting a new bolt.

I am suprised you didnt shatter the bolt making it really cold like that. Steel doesnt do as well when it is cold vs aluminum. I was sitting in on my friends Mechanics of Materials class last semester and the teacher was explaining how steel is very brittle at lower temperatures, and aluminum has a broader range of where it is flexable, similarly that is why airplanes use a lot of aluminum because they operate in very cold temperatures as well as very hot temperatures (-60 to 60 C or so).

But heed the advice on getting a new bolt.

__________________
Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.