It sounds like the clutch just needs to be bled. If it isn't leaking fluid from the slave cyl. it is probably fine. If bleeding it does nothing then perhaps the master is bad. Unless you have the internal slave (probably not), I would only replace the defective part. The guy who did your rear shaft probably got paid for both joints... Whenever I replace parts I just fix the broken one and save my time and money on the good one(s).