Possible Clues:

• 'Hey, didn't see you there ...'
• “When’d you come in?”
• 'Didn't see you there ...'
• Greeting before 'I didn't see you there!'
• Greeting before "I didn't see you there!"
• Response to "Fancy meeting you here!"
• Somewhat surprised greeting
• Surprised reply
• 'I wasn't expecting you!' lead-in
• 'What a surprise to see you!'