left front caliper freezing?

i've been driving my 88 xj for about 2 weeks now and it seems that i'm getting a problem from the drivers side front brake. It actually started working better and when i get to a low speed during a stop ( less than 5mph) i get a low tone squeel. I checked the brake pads about a week ago and they looked to have about 50% left. unless i missed something.

i'm curious as to what the cause of this is, its almost like it wants to lock up when i start to press the brake pedal. i'm thinking its not bad pads due to the fact that is working better. i'm not sure if this is the first sign of a caliper starting to freeze up because i've never had one do it to me. i've fixed a few in my time but never had one of my own go. it Jeep rolls freely and doesn't seem to have a stick spot when just coasting or when i toss it in neutral at the top of a hill.

i havent jacked it up yet to see if i can spin the wheel by hand.

TIA

Your front brake hose could be collapsed inside wont let fluid back out of calipher.

Did you clean up and anti-seize the slide bolts when you checked the break pads? Sometimes they will just freeze up inside the rubber boots and lock the pads against the rotor.