Hiya ,
My 1.6 runs at 90 - I think most thermostats are set around 88 - 92 - sometimes engines run a bit hotter when they are new - 100 sounds too much- does the cooling fan come on ? - it could be the guage - they usually read mid way for normal , have you checked cooloant level - I know it's a new car - but worth checking - if it stays that high I would contact the dealer.
Rich