(T) Engine problem or paranoia?

Just bought a new 1.2 active, one of the stripes editions. It's only 5 weeks old now, with 1300 on the clock, but the last 100 miles or so the engine pitch has changed when i apply full throttle. Regardless of revs or speed, the moment i put my foot flat to the floor the engine note is now a bit deeper or 'throatier', like it's suddenly had a bigger exhaust put on. Has anyone else noticed this about the 1.2's? Should i get it checked or am i just being over cautious and paranoid about my first new car?
Any help or thoughts would be GREATLY appreciated.

I would get it checked, given its new something could have been missed or not tightened up properly when it was built.

I tell you what mine does that gives me paranoia....when sat in the car with the engine running, when it ticks over it feels like its about to shoot of like a rocket and stops. Like bursts of energy but not going anywhere. Probably not described it best like

No, i think i understand what you mean. Mine seems to run a bit rich and want to go off like a rocket too sometimes.I'm gonna call the dealers about it anyway, get it in for a look. It's started to sound like the air intake or something. Maybe the air filter's not connected properly.

You mean lumpy/erratic idle?

Check your MPG aswell wih regards to whether it's airbox or exhaust issues.