Check your mounts and harmonic damper.
The other thing is spark plug tightness; other hondas have been known to shake them loose if they're not correctly tightened.
Although I would say that the 90 degree offset crank gives the thing an idle like a Trabant & the steering column vibrates like an early Diesel Golf! It's no BMW straight six. It gets very smooth over about 1,500 rpm though. Maybe in the cold weather, you've become more aware of this.
Nick
“I find myself irresistibly attracted to cars that nobody else buys. The NSX is a classic of the genre because nobody buys it and yet it’s a fantastic car. It’s got a wonderful compactness and simplicity and unpretentiousness to it. Honda rudely continues to make them whether we like it or not, even though there can be no commercial logic in doing so — I thoroughly admire that.” Rowan Atkinson