That is, when I'm home and someone I'm used to seeing often is away, or very busy, so I don't get to see them for long periods of time, I miss them. But when I'm traveling, I'm not used to X person being in Y place, and therefore, there's not an X shaped hole where I am.
I think I missed my parents when I went to college, and I know I missed aspects of being home when I went to Guate, but overall, and especially during short trips, missing just doesn't come in for me, unless I'm traveling somewhere that I'm used to seeing a certain person. If I were in CA, for example, and kcatalyst and trom weren't around, that would, no doubt, be weird for me; and when I went back to Guate, it was odd to be in Xela but have lots of my friends not be there, and I missed having them around, but if I'm not expecting a person to be in that context, then it doesn't occur to me, emotionally, to miss them when my expectations are met.
This leads to things like, when I was in Guatemala, friends telling me they missed me, and my most equivalent response being, "I'm looking forward to seeing you!" Which was completely honest, and heartfelt, but I suspect it fell flat for the missers, since, really, the feeling of missing someone is much more present and urgent than simply looking forward to seeing them.
I think about this a lot when I'm doing more travel, which I have been recently, leading me to not seeing lots of you as much or as recently as I might like. I'm looking forward to seeing you.