Nope, not Timbuktu! But I did get the feeling during that ep that before Lorelai spoke up to him about trying to have a good time and all and talking about how she needed to hear once in a while that he loved her etc, how Luke was behaving was to show how much he was busy in his mind with April. He really wasn't into this trip, because he was not so much aware that he was in a relationship with Lorelai, but was more busy in his mind with the whole April situation. Logan was the first to hit him on the head with the remark he should have gotten his girl a present and well later Lorelai spoke up. From that moment on he sort of was aware of also being in a relationship or so it felt to me and again enjoying himself and Lorelai, until they arrived back in SH and his mind wandered again to April and well Luke was not so much there again ...

So I am thinking the way Luke responded during AVV was more about him in his mind not being in this relationship or not so aware of it, and not so much about him having a problem with travelling ...