We?

Ive noticed for quite some time now, something many people say when speaking in a second-learned-language. My mom (shes Polish) always says this when speaking English, not her native tounge, but I got used to it, and though it was just something she said. Recently, Ive noticed the same thing with a Russian neighbor who says it when speaking German. Being again aware, Ive been noticing the same thing among other fellow foreign Students.

"We went to the store with Martin..."

But the person saying this, means "I went to the store with Martin...". At the beginning I was always confused, wanting to know who else was there, but the response was always, well...just me and Martin.

Is this something you say in your language, and its only something that I am unfamilar with, or have you noticed this in similar or other cases?