'01 Honda Civic with sunroof, my headliner was kind of damp, should I be concerned?

I bought an '01 Civic this past summer in excellent condition. This is the first winter I've had it. A couple of weeks ago we had a major major winter blast and my car got smothered in snow. I don't use the car everyday and its parked outside. So it sat a few days and I let the snow melt itself off the car. When I got back in the car, I noticed the headliner was very damp, especially on the driver's side. Not dripping or anything, but visibly wet. I was a little scared. This past weekend we had another blast of winter, nearly 20 cm of snow landed on top of the car. Again I let it thaw itself out (this time on purpose). The headliner? Not damp at all. I'm just confused. Maybe there was too much condensation in the car the first time or something. I plan on doing a full servicing at the dealership in summer, but I'm not sure whether to act on this now before it gets worse (whatever "it" is) or ignore it. Comments?