Please take a look and a listen for me.
Sorry to be a pain.
Sounds fine to me, nice low growl in the movie
As its still under warranty ur best bet is to take it back and see wot they think. Me and my dad both have 1.8 sri bout six months apart and they sound nothing like each other, so it may be nothing. But as its under warranty its worth a check especially as vauxhall are having a s***t load of trouble with there newest range of engines.