welcome, danzina 
Unfortunately I haven’t experienced this… I think. It reminds me of this one things that I have experienced, but it seems a bit different. Now that I think of it it probably was related to fever and SP as well… I would describe it as … ok, I don’t know how to describe it, it’s so hard! When I read “soft” above it reminded me of this, but for me it feels a bit like… cloth? Maybe it was just the feeling of my sheets, but it’s like I’m feeling it with my mind and not with my skin. I’m not really sure, it might just be the same thing and the words used are confusing me 
Although it never made me scared (that I can recall), only perhaps a little unconfortable and confused. Now a days I also have it very rarely when falling asleep.
Even though you/we might never have felt SP with this feeling, it’s quite possible that it’s “just” HH, which are natural hallucinations you get when you’re close to falling asleep (often come with SP). Although it’s weird that it would be a “common” thing, relatively speaking, of course, compared to the infinite possibility of random HH you can get…
Anyway, I wish it is what I experience as well, since I could never find anyone who’d had it or any way of describing it… There’s also the “big state of mind” topic here, which might be related to this (even if distantly).