I went to clean my bolt today and I can't remove what's on the picture towards the bottom. It almost looks like it melted? 

Only about 1000 rounds through the gun. Can I just switch the bolt without checking headspace? Its still relatively new. Its 

That's just carbon build up. Not a big deal. It is one of the consequences of a DI system.

A tool like this makes cleaning it much easier.

https://www.amazon.com/CAT-Outdoors-Scraping-Scraper-Cleaning/dp/B09QY26MKS

Normal carbon buildup like @Mr.Stu said.

You can leave it alone. It does not impact the function of the gun. The bolt will fail/need to be replaced before it builds up enough carbon to effect function. 

If it bothers you, the CAT Tool linked above works well, but it also adds unnecessary wear to the bolt tail.

Make sure the gas rings and extractor are in spec. Then wipe down the firing pin, clean the lugs and bolt face, wipe down and lube the rest of the bolt. That is about all that is needed.