It could be, although I'm wondering if you are " warming " the bike up by letting it idle a few minutes with the choke on ? This is not advisable. Ride way immediately on starting, and close ( turn off ) ther choke a.s.a.p. Leaving the choke on for too long will flood the carbs ( and ensure your pistons are getting less oil, essential when cold ) and is MAYBE the cause of your grief.
Keep the revs very low for the first mile or so.
Popping in the exhaust when closing the throttle could indicate holes in the exhaust system.
If not the above, then yes, it sounds like icing! There are little warm up heaters attached to many new bikes now, and perhaps you could consider buying these. The bike manufacturers blame our petrol for icing, and they have a pretty solid case. There are additives, too, but I have little experience of using them. Silkolene's additive had a good review.
Still, watch that choke first!!