So, 2 years ago on August 4 I took the train up to New York City and had the best night of my life. I met up with someone I had gone to high school with but never knew, we had a conversation at our 10 year reunion and exchanged numbers. Later that year we met up, went to a concert, and she invited me to come up and hang out with her (which ended up being August 4). I didn't know that August 5 was her birthday when I went up, but she told me during dinner. The rest of the night was great, we had a lot of fun. I woke up in her bed the morning of her birthday...we didn't have sex, but things definitely got physical.
She moved home since then, around a year and a half ago, to go back to school. I expected something to happen between us, but it never did. We lost touch, but recently started seeing each other again. We're 'taking it slow', but there seems to be mutual interest in seeing where this goes.
I want to do something nice for her birthday. I'll never forget the date, its burned into my memory. Though, I'm kind of worried that if I come up with some elaborate scheme it will be creepy, and worried that its creepy I even remember. How would you approach this?