I was rewatching the episode "Flashes Before Your Eyes" last night. That is the one immediately after the hatch explodes and we see Desmond travel back in time for the first time.
When Desmond enters a ring shop to buy an engagement ring for Penny he is greeted by Ms. Hawking. This is the first time we ever see her in Lost, read her very first words carefully.
MS. HAWKING: Never done this before have you?
DESMOND: Is it that obvious?
MS. HAWKING: I can always tell the first timers.
To Desmond and a first time viewer it sounds like she is talking about buying engagement rings. To Ms. Hawking and the Lost expert she is most likely referring to Desmond's time traveling. Hadn't seen this posted anywhere else on Lostpedia, another very cool hidden meaning.