What’s an author to do?

I was in the gym last week, running nowhere on a treadmill when I noticed that the woman beside me was reading SOMETHING MISSING. 

I was thrilled.  One of my first discoveries of my book “in the wild.” 

But just as quickly as the adrenaline shot through my body,  I was stuck. 

What to do?

As a reader, if the author of a book that I was reading was standing beside me, I think I’d want to know and would hope that he or she would speak up.

But as an author, it’s not so easy to look across exercise equipment at a complete stranger and say, “Guess what?  I wrote that book.”

Is there any way to let a reader know that you are present without sounding like a stalker or a loser?