Celebrate with Joy

Advent 2011 day 25

Luke 2:10-11
And  the angel said unto them, Fear not: for, behold, I bring you good tidings of great joy, which shall be to all people.
For unto you is born this day in the city of David and Saviour, which is Christ the Lord.

We were at the Christmas Eve service last night (yeah, it's a few days before Christmas, but Crossroads has a few extra services). This was a little different than some that I've been to. Usually, they are fairly solemn occasions. Not that they are like a funeral or anything, but they are a little more serious.
Last night though, as the pastor was talking, I suddenly started to see flashes of light from a few people down my row. Turns out, my sister and her friend had lighters out, and were randomly flicking them on. And from that point, the service was a little lighter (in more ways than one...) than most that I have been to.
During the part of the service where we had a chance to go and make amends with people if we needed to, the people in our little section of the church mostly just goofed around. We didn't need to make amends, so we just had fun being together.
And then we came to the candle lighting and Christmas Carols. At that point, the lighters came in sort of handy. Especially when candles were blown out. And we were deliberately trying to blow out each other's candles. There was more giggling during this service than there has been during others that I remember.
And is there a problem with that? Where does it say that Christmas Eve services are supposed to be serious? I actually think it was good. The angel brought good tidings of great joy. Why shouldn't we celebrate with joy?