Selcuded behavior on holiday

Can't understand why dh is remaining off by himself today. Yesterday was a touch and go day - he spent a large part of the day outside (removing snow) and when he was around - it was touchy as to how he would react to things - but overall he was okay. He enjoyed himself with his family - he said so. So why now today is he choosing to be unplugged from our family?  He hasn't done anything with us today. The kids and I played games together and invited him to join us - no. He decided to get a movie instead and watch that in the same room as we were playing our games. He went out for a 2 hour snowmobile ride. Our son asked him directly for help setting up his new Xbox - he sat there, son asked again - No, you can do it. So son asked me to help him. I waited to see if my dh would at this point say he'd help, but no. So I helped son put it together and watched him figure out the controller and games and just enjoyed his happiness with the new toy.  As we are finished setting up dh decides to see what we are doing - but doesn't stop to see just keeps walking on. He isn't interested in playing with any of the kids toys with them. So after his snowmobile ride he decides to watch a movie and eat. After that, he falls asleep in the recliner for an hour.  He wakes up walks to the back bedroom and crawls into the bed, I ask him what's wrong - I'm tired. Oh, well why don't you got upstairs to bed. Why, what are you going to do? My reply - not much, just hang out with the kids. I'm not sure that he realizes that his has missed out on the joys of the holidays - seeing the kids delight in spending time together. We had a blast playing games-laughing and teasing each other and of course seeing who won.  He is snoring in the back room right now.  So why all of this avoidance today? I feel bad that the kids notice that dad's not around/asleep/distracted with his newspaper/magazine,ect. I think I feel even worse that they are beginning to get used to this.  Is there something about the holidays that affect ADDers?