It's good idea to use your common sense when it comes to following up with people. I have had people call me with the "we met at the ___ airport and I just wanted to keep in touch" pitch. It irritates me when I get these calls as my phone rings enough from the office, bosses etc. Kind of like a telemarketer call on sunday morning. If you really hit it off with the person or they tell you to call that is another story. Email with an updated resume always works.