2013 Jetta front caliper piston sticking

Has anyone else had this issue?

I noticed last summer that my MPG's were not getting better as the summer temps started to warm up. After taking the car on a 5-600 mi trip and getting 4-5 mpg less than expected I decided to try and figure out what was going on. I found the front driver side brake was clamping down hard on the caliper. I took everything apart greased the sliding pins, and compressed the piston. The piston was very hard to compress at first, but did loosen up. After doing this the MPG's came back to normal.

Last week I noticed again the MPG's dropping, and sure enough the caliper was stuck again.

Do I just need to put a new caliper on, or could there be anything else causing this problem?

I had it happen in the rear, there was a dust boot on the piston that was letting water in and causing a little bit of rust in the bore between the dust boot and hydraulic seal around the piston that would make it bind up, I took it apart, cleaned it, put some grease after the hydraulic seal and replaced the boot and never had another problem. think the rebuild kit cost 6 dollars.