What have you ordered?
Alcantara can wear quite badly (from the A3s i have test drove before i got mine).
I have the hole-ly cloth one with half leather in my S-Line and seen leather on leather and they're awesome - As long as its one them 2, it wouldnt bother me.
I wouldnt worry too much fella!
If it really does bug you - I spoke to a a sales rep about an A3 i seen at Audi and it didnt have leather i asked on the cost to redo was around £1500 to £2k.
HTH