4 months after beard transplant and some hairs have fallen off occasionally, is that normal?

It is normal for the transplanted hair to shed.  After the surgery, the hair will enter a "sleep phase" where there is no hair growing. At eight months to a year, you should see fuller results from your transplant.

Beard transplant hairs can shed at 3 weeks or as late as 4+ months. Likely, you are experiencing telogen and the hairs will regrow. At 1 year from surgery, you will have  good sense as to your result. Best of luck!

These hairs will sooner or later shed. They are never a problem for new hairs that start to grow. Usually, there is a lag time between the time the hairs shed (2-8 weeks) and the time the new hair grows (3-8 months). IF for any reason, there is an overlap between the two, pay no attention to it for when the new hair grows, the old hairs from the grafts that may persist beyond 8 weeks, will eventually shed