How to solve anchor points at the end of a line?

Hi,

I was drawing a logo on my PC today using paint bush tool. Then I asked my girlfriend to take a look and make some changes, so she used her iPad adobe illustrator to make some changes. However, when I open the document she modified, all the lines I drawed with paint bush have two anchor points at the end of the line, so I cannot use direct selection tool and pen tool for this document. Can anyone help me solve this problem? I need this help because me and my girlfriend need to work some projects together.