Proper Etiquette For Laughers

I had a question last night about ethics and etiquette, what a person's supposed to do.

I was at the exercise place, on the treadmill, listening to my Ipod. Less than four feet away, probably three feet, is an exercise bike and a woman sat down to exercise. We're over in the corner alone. No one else on the treadmills, but there is another woman behind us on a machine, probably six feet back.

The woman sits to exercise on the bike and she's watching TV. She's watching something that is extremely funny because she's laughing loudly and persistently. Even though I've got the Ipod going and it's clear that I have earbuds, I can hear her quite well.

So I'm suddenly wondering if there's an ethics and etiquette issue, unforeseen or I would have taken a different treadmill. Do I look over and see what's so funny? Is it a case where I need to take the earbuds out to share in her happiness? Would it seem like I was encroaching in some way, since we're so close? Is it kinder to ignore her and pretend like I'm absorbed in my music.

To complicate things, my coats and possessions are on the floor in the space between us, a narrow space. When I get done (I started before her) I'm going to need to get in that narrow space and get my things, meaning my butt might be in her face, moderately so. I don't want to look like I'm invading her space, etc.

The laughter continues. I glanced over once, ready to smile if needed, but she was looking at the TV, just laughing. No eye contact. I'm very uncomfortable, but kept going. Finally I decided not to do the whole cool down routine but cut it off so I could get out of that corner.

Getting my coats and stuff, I muttered "Excuse me," and noticed that she was watching The Daily Show with Jon Stewart, an interview segment. She never seemed to notice my presence there, although she had to have.

Laughing, laughing, laughing. Hard to believe I could feel so consternated at someone else's happiness. But it made for a weird feeling, since there actually are numerous social issues going on.