help! packet sniffing explanation needed

I work at a busy coffee shop with free wifi. I posted something to craigslist looking for advise on a personal matter while I was at work. This isn't an illegal or particularly unusual problem, but given some of the details I decided to post in a different city and from my junk mail email address just in case.

I just got a reply to the message from my manager- a girl I'm friendly with.

I felt violated and confused. I did a little research and came up with packet sniffing as the likely culprit.

What I don't understand, though, is how she sifted this out of all the nonsense people look at on their computers all day long. There are an average of 25 people on the wifi at a time, 16 hrs/day.

Please help me.

Btw, this is clearly not posted from the coffee shop.

 

Sure it wasn't more low tech like shoulder surfing? Does she have access to the computer you used?

 

I posted from my blackberry and she wasn't even there to look over my shoulder to read it or anything.

 

And your BB connects to the local wifi? I'd figured it would use your data plan. Maybe they do some traffic monitoring on their wifi, nowdays it is probably a government mandate, so Osama Jr can't sip a latte and plan a jihad.

 

I don't have a data plan. I snuck in before phone companies required them. It's pretty much an ipod touch. It does wifi.