
The caliper rides on two posts -- numbers 5 and 7 in the diagram. The posts have flat areas to make room for grease. The small rubber boots help retain the grease and act as wipers/dust seals.
In theory, the caliper is free to slide in and out on the posts to adjust for variations in the rotor. Also, since only the outside brake pad gets pushed, there needs to be some slack in the caliper mount to allow it to squeeze and release. But the grease can get thick, so the caliper doesn't always release fully. That's part of life with this type of caliper.
Also, the piston seals might get gummy so the piston doesn't retract much when you release the brake, leaving the outside pad dragging more than usual.
So you might at least freshen the grease on the posts. Remove the caliper from the fork and pull it off the bracket. No need to disconnect the hydraulic line. When you put it back together, make sure the ends of the boots tuck into the grooves so you don't lose grease over time and so crap doesn't get in to gum up the grease.
Cleaning or replacing the seals means taking everything apart, which is another story.