Sod's law indeed!
I can't see it being to do with the speed though - I did 108 on the '03 last summer... and had no problems till mine was hit. And that was at around 9500 miles on her.
If it is a cracked cylinder I would suspect it is due to the smack...but I'm just really cynical at the mo.
Gina
03 America - Pretty stock - except the TBS wheel...

06 America - missing, presumed in bits. With it's TBS wheel...

09 America - It's very blue....