Originally Posted by MattTHEpainter
Those are called "spider-cracks" and are usually in the substrate of a plastic part. You will need to sand down to plastic, and see if they are still visible. If they are, sand a little more. If they cant be sanded out in the first few mm of plastic you will need to "V" out the cracks, then use SEM Problem Plastic to fill them. San smooth then use some flexible polyester filler. High build primer, then spray. Luckily this is all below that hard line, and you could probably keep it very unnoticeable. Let me know if this helps, or you need further clarification.
Perfect. It makes sense now, so maybe once I get started I'll let you know. It just snowed a ton, so I may not get to it soon like I wanted though...