Hmmm...good question.
Carbon fibre is resinous like glassfibre. I've got an old trials bike where the exhaust runs directly under a glassfibre tank/seat cover and that's OK, and if you think about it thay make carbon cans (although the gases have got a bit of volume to cool a bit).
Don't think it will melt, but it may well discolour and go a nasty brown colour - I'd space it if I were you