You're welcome. Now that you've said they've been sneezing as long as you've had them, I feel a lot better! I'm almost sure it's the detergent/fabric softner. Hair spray will also make my dogs sneeze.
I'm sure that you're right, they had the URI, or at least Daisy, and now they're just sneezing because they're sensitive to whatever they're smelling. Make sure that you're also washing the towels underneath in the same manner as the fleece. Along with any cuddle cups/snuggle sacks or whatever you've got. I would also take it one step further and do a complete cage clean/wipe down. Take out the pigloos and toys and spray them all down with a spray bottle filled with a 50/50 mix of vinegar and water (if you can't spray it and wipe it down, I'd consider replacing it, or at least leaving it out for a few days while you do your "test run" to see if it's the fabric softner/soap). Then strip the cage and do the same for that, spray it all and wipe it down. This may be more than you need to do, but I would, to make sure there weren't any particles on anything that would continue to make them sneeze after I'd washed everything.