I believe this is The Nostalginauts by S.N. Dyer, published in Asimov's March 1997 edition and republished in Year’s Best SF 3, edited by David G. Hartwell (1998). There's a free audio version [here][1]:

When time travelers first started showing up they were called phantoms. When scientists figured out what they were, the media called them time tourists, or nostalginauts. We stuck with phantom, pronounced phan-dumb, and finally just dumdums.

 

I mean, what a phenomenally stupid invention. Time travel that only takes you twenty-five years into the past, lasts half a minute, and you’re insubstantial too. It makes a quest for rubber beverage containers look intelligent.

And, the ending:

But I still had my patented sardonic grin, as my future self flashed up something white.

 

“Not pictures,” I moaned.

 

No. It was an index card. My handwriting didn’t seem to have improved either. I’d scrawled, “IT HASN’T BEEN DULL.”

 

I shrugged at me and disappeared.

 

It hasn’t been dull.

 

Cool. I can live with that.

It was also one of my faves and both it and the title have stuck in my mind. [1]: http://ia802607.us.archive.org/31/items/SETheater/S.E.T._38_The_Nostalgianauts.mp3

I believe this is The Nostalginauts by S.N. Dyer, published in Asimov's March 1997 edition and republished in Year’s Best SF 3, edited by David G. Hartwell (1998). There's a free audio version here:

When time travelers first started showing up they were called phantoms. When scientists figured out what they were, the media called them time tourists, or nostalginauts. We stuck with phantom, pronounced phan-dumb, and finally just dumdums.

I mean, what a phenomenally stupid invention. Time travel that only takes you twenty-five years into the past, lasts half a minute, and you’re insubstantial too. It makes a quest for rubber beverage containers look intelligent.

And, the ending:

But I still had my patented sardonic grin, as my future self flashed up something white.

“Not pictures,” I moaned.

No. It was an index card. My handwriting didn’t seem to have improved either. I’d scrawled, “IT HASN’T BEEN DULL.”

I shrugged at me and disappeared.

It hasn’t been dull.

Cool. I can live with that.

It was also one of my faves and both it and the title have stuck in my mind.