I don't think big loops will disappear in the wash, but the small ones might. You might be able to use one of the tools with a tiny hook at the end used to repair knits. Slide it in where there's a seam, snag the thread from within the quilt, and pull the excess to the inside. I don't know whether it would work, but it's worth a try.
Here's one brand of the tool I'm thinking about -
https://www.walmart.com/ip/Dritz-Sna...&wl13=&veh=sem