Good for you for showing son that while changed - as most things will be - this tradition goes on. There's comfort and security in tradition and ritual for young ones. Old ones, too. I'm not surprised that on this first non-family trip, W is "tresspassing" onto your mental real estate.
That will abate - in all areas - with time. I find that since my mental real estate is finite, the more I fill it with other, newer positives, the less room there is for any of X's old "squatter's rights."
Enjoy! Have a giddy blast!
Gardener
"My soul, be satisfied with flowers, With fruit, with weeds even; but gather them In the one garden you may call your own." Cyrano deBergerac