Fueling problem?

I've recently got a brand new America, and had the short slash cut pipes fitted from the off. So far I've only covered a couple of hundred miles, so it hasn't been in for it's shakedown service yet, at which point I'll mention this slight problem.
On partial throttle I've been occasionally getting a slight 'missing' feeling, which I suspect is down to the fueling being too lean. Hopefully the dealer mapped the ECU for the pipes, and I will mention it when I take it in, but has anyone else experienced this? The engine is the 865cc A3 version, and the pipes are the Triumph accessory short slash cut option (TOR's?).
It only occasionally happens and it is only on partial throttle (I'm being gentle with it, running it in!).
Any thoughts, observations etc. welcomed.

 

Che

Cheers - I've seen the threads and videos on removing the secondary air injection system, and that might be a route I go down in the future, but as it's 'box fresh' I'll see what happens after it's been run in and I can give it a bit more of a ragging.

 

Update - it's been in for the 500 mile shakedown service and there was a problem with the ECU settings. I was getting a backfire on #1 cylinder, but not #2 when rolling off the throttle, and there was a hesitancy, like it was hunting, on partial open throttle. Anyway long story short, it was mentioned as I took it in, the guys at Pure Triumph Birmingham rubbed it with their magic oily cloth and it's spot on now. The service sheet readout said it hadn't adapted to the TOR's, so they forced it to adapt! Happy days, it is running as I expected it to now. Time to twist that grip a bit further and rack up more miles now.