1950 3100

Replaced front wheel cylinders 300 miles ago. Brakes seemed to function acceptably.
Was not able to drive truck for about 3 weeks.
Took her out one afternoon and found that I had a hard pedal and brakes were dragging.
Jacked up front end of truck and found that driver side wheel was locked up.
Pulled hub and sure enough shoes are locked.
Master cylinder seems to function.
Could I have purchased a defective wheel cylinder?

Thanks for any info!

Kurt