Is it normal to still have tan lines even 4 months after tanning?

In the begining of June I swam in the red sea for like 8 hours and it was extremly hot and sunny ( around 43 degrees celicius or 110 degrees fahrenheit, I burnt) I wore a short with my swimsuit, so now it looks like I have long socks on T_T It's extremly obvious because I have light legs...
Is it normal to still have tan lines even 4 months after tanning?
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