I haven't taken Propecia for two weeks after hair transplant. How bad is this?

Thank you for the post. You should be fine if you only missed for 2 weeks as the medication will likely still be in your system. Highly recommended you start the Propecia/Finasteride when you are able to. 

Shock loss is not very common.  Propecia does make it less likely and should be taken if possible.  I agree that resuming it at this point is better than just stopping it.  Continued use can also prevent or decrease further hair loss.