That is the correct location for the Lane Departure camera, but it doesn't look like the OEM part. Check out the diagram of the KaFAS camera here:
RealOEM.com * BMW E70N X5 40dX KaFAS camera
If you google the part number you can find pictires of the actual part and it looks different from what you have installed.

Is there any chance it's aftermarket?

Or perhaps part of this retrofit?
RealOEM.com * BMW E70N X5 40dX BMW Advanced Car Eye

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