Most reputable repair shops and dealers will warranty their work but a problem that pops up after 1300 miles of driving is not always their fault. Calipers failing is one thing that they would not be responsible for. However, if they did not check and lubricate the caliper slide pins then they are at fault.
I have been doing my own brake jobs for the past several years after a few decades of paying to have it done. The cost was too high and the quality of work was poor far too often.
I have never heard of a Master Cylinder Failure causing calipers to freeze. Calipers usually freeze up because the brake fluid gets so old and contaminated that it causes the caliper to bind from corrosion or particulate/contaminant. Calipers also freeze up if the slide pins are corroded and/or are not lubricated properly. The slide pins should be removed, inspected, and lubricated during every brake job.
Most people don't do this but I have started draining and refilling my brake fluid at least every other brake job. With 50,000 miles on your Liberty, you should have already drained and refilled your brake fluid at least once. You can check the recommended drain/refill interval but 24 months or 24,000 miles would probably be about right. I switched all four (4) of our vehicles to premium synthetic brake fluid this year. Good Luck!
Source: 33 years of personal experience