This must be taken in context. The other lyrics are:
"You'd know how the time flies.
Only yesterday was the time of our lives.
We were born and raised in a summery haze.
Bound by the surprise of our glory days."
She's looking back on their time together - their time together seemed like it was just yesterday. Yesterday, their love was wondrous, beautiful, amazing. They were happy together - like they were in a 'summery haze'. They were surprised at how wondrous it all was, surprised by their 'glory days'.