Yeast rafts after 4 weeks in primary?

So I cracked open my chocolate stout last night to check the FG (1.018, it was at 1.020 after the first week so I'd say that's good and done), but there were still yeast rafts on the surface now like there were after a week of fermenting. Not just a few of them like I'm used to, but they're covering the entire surface with about 1/8" to 1/4" spacing between each. Do these guys just never fall down? The beer tasted great and was pretty clear in my hydro sample, so unless anybody says to not bottle, it looks like I'm going to be drinking it in about ~3 weeks.

Sometimes they just dont fall out especially with certain yeasts. A good cold crash may help, but may not. don't sweat it, just siphon from under them.