Is this line on my upper lip after laser hair removal normal? (Photo)

It is difficult to determine from the photograph if the pigment is lighter than your normal skin or if the surrounding edges are darker from post-inflammatory hyperpigmentation.  Use a sunblock and don't try to get it darker from sun exposure as it can make things worse.  Textbooks say that hyperpigmentation (darkening) usually resolves but can take a couple of years, but that hypopigmentation can be permanent.  A board-certified dermatologist might use a Wood's light to see if there is some pigment remaining which may indicate a clinical improvement can still occur.
 

Hypopigmentation (lightening of the skin) is a potential side effect of laser hair removal that can be temporary in most cases or occasionally permanent.

Side effects from laser hair removal increase with increasing amounts of pigment present in the skin, such as may happen after sun exposure.  The patient should not have any sun exposure to the area for one month before and one month after each laser hair removal session.

Potential risks of laser hair removal include temporary or permanent hypo-pigmentation or hyper-pigmentation. This can occur even when optimal laser treatment parameters are used. Fortunately most instances of pigmentation changes are temporary and tend to blend in over time. We instruct all our patients to make sure the area has had no sun exposure for one month prior and one month after the laser procedure. Daily use of an effective sunscreen is key, regardless as to whether you are going outdoors.