Mike Stone starts with a small, happy surprise: the seasons turning, the earth easing away from summer heat toward winter's cool. Then an ordinary event interrupts it. His dog, Daisy, snatches the leash from his hand, pleased with herself and with the walk they've had. The speaker almost misses all of it, and that near-miss is what the poem is really about.
From there the tone shifts to a quiet, anxious question: "Is this it?" Which moment will he carry for the rest of his life, and which will simply outlast him, remembered "instead of me"? He can't tell in the moment, and that uncertainty is the heart of the poem.
The ending is the most tender part. He admits he almost missed the look of a loved one's smile on the morning she changed "from young to old." The mood is warm but touched with regret, a gentle reminder to pay attention while important things are still happening.