and a NEW YORK POST with her face on it (line 25)
Then it happens: the speaker sees the newspaper, which triggers what the French writer Marcel Proust called "involuntary memory." (Judging by the speaker's love of all things French, you'd better believe he has read Proust's massive novel Remembrance of Things Past.) The newspaper sends the speaker plunging back into a memory of a concert.
And I am sweating a lot by now and thinking of leaning on the john door in the 5 SPOT (lines 26-27)
Now the speaker goes down the rabbit hole, and the setting of the poem suddenly shifts from present to past.