Unless you ate an additional 14000 calories, then you did not gain 4lbs in 4 days.
Probably, the skiing is causing your body to retain some water, you may have changed your sleep patterns, my physican also says cold weather can induce some weight fluctuations.
The scale and I have a love hate relationship for this reason. It really is just a number and as frustrating as your weight is reading on the scale, it will change shortly and the numbers will go down.
Try not to take it to heart