VXOC Astra-J/GTC

So when i drive from work to home and the car is cold it sometimes stops accelerating for a split seccond usaly around 70 kmph, sometimes it happens wile i'm allready at speed.
it only seems to do it when i'm on a late shift and happens only in the firts minute.
any ideas what i could be? probably going to the dealer tommorow.
thanks

edit: i have the 1.4 turbo petrol

took it to the gararge, they said there is nothing worng and that it is the EGR valve that starts working or something like that.
Nothing to worry about because it's only when the car is cold