My interview started out great. But then I started overanalyzing the situation: getting anxious when they weren't writing after I answered a question, or when I thought the interviewers exchanging looks. Long story short, by the end of interview I was feeling terrible, so I think I forgot to shake their hands. I think I whispered a thank you and walked out. I, also, really got distracted by the writing. I caught myself looking at their paper for more than 30 secs once, so I hope they didn't think I was trying to read what they were writing down. My answers were fine, but everything else was meh.