My girlfriend talks to herself in the shower, anyone else's SO does this?

I was walking by the bathroom today and I heard my g/f mumbling to herself, or what I thought was mumbling. I thought she was on her cell phone in the shower, but I noticed it on her desk. After cracking the door open just a bit, I heard her talking to herself about me and our relationship, things I said to her over the last few days and generally voicing her feelings towards things. She did this non-stop for about 5 minutes and then would rest. I know it isn't nice to eavesdrop, but when I hear her real honest responses to things I've said, it kind of saddens me that she's not being so open with me. Anyone else have this problem?