Can I get some help with my pants? Sewing Machines Parts and Sales in Los Angeles

In the pictures I posted, it appears that the left side of the pants seems to be attach to itself. I looked closer, thinking it was something sticky or residue, but it turns out to be some stitching. I looked at the other side of my pants, and they looked normal though, so I was wondering if this is normal. I just noticed this now, even though I bought these pants 6 months ago.
Thanks!

The left side (the problem)
http://imgur.com/a/CN8Ql

The right side (the “normal” look)
http://imgur.com/2YONvDy

left inside
http://imgur.com/1L4JHn0

right inside
http://imgur.com/JJ7BPYU

edit: added inside