My A3 doesn't seem to have a stiff gear change at all, but an Octavia I had before was very stiff coming out of reverse when cold when it was brand new. That loosened up nicely over a few thousand miles and never caused any problems long term (I had it for 8 or 9 years). I guess if I were you I'd wait and see if it loosens up over the next few months. If it doesn't improve at all then maybe there's an issue, but hopefully not!