Is this a receding hairline? (photos)

Thanks for posting pictures. It really makes for a more meaningful response.  In looking at your hairline, there does appear to be thinning known as "frontotemporal recession", which is thinning at the triangles along the sides of the central hair.  You are at a great point to consider treatment.  Treatment should be focused on not only maintaining your hair, but also making your hair look as good as possible now.  Take time to find a hair doctor that will give time and guidance as each physician has a unique style and approach when it comes to hair.Very best,Dr. Paul

Seems to be a receding hairline at Norwood 1. As you have not mention about your age it is hard to say something if it will be progressive.Better to see a specialist for the diagnosis.