Modern Vespa

So I've had the new 310 for nearly 6 months and done 2,400km. I'm riding it more now as the summer is here! My problem is when I'm riding at a constant speed and not moving the throttle position at all, occasionally the revs slightly drop and the speed slightly reduces, nothing much but enough for me to notice - 2 or 4 kmph. I can accelerate again and it's fine but it's annoying me! I will take it to the dealer but wondered if anyone has had a similar problem or any ideas? It's not when I'm going flat out, often notice it more at around 100kmph or 110kmph (Vespa Speedo!). A friend said maybe the traction control but I've tried it with that on and off and there is no difference. I thought maybe throttle cable (if these still exist! Or fuel injectors), and of course the worse part - it's "intermittent" so not always happening!!
Cheers.

There's a thread on the German forum that sounds similar

https://vespaforum-de.translate.goog/viewtopic.php?f=15&t=65597&sid=50e643387e6e76ffa199154f66038bee&_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp

Thanks SteelBytes I've just read through all of that thread.

Good news - seems to be a fault that quite a few people have mentioned.
Bad news - no fix yet!

I did see some mentioned about the belt maybe slightly slipping and others with various different thoughts. I'll get it booked in the with dealer and see what he says.