If the workload on your machine is going fine, then there is nothing to be concerned. There could be just WLM inner traffic, and if a job is not first in the queue it sends a message 'Transmitter busy'. After this job became the first "in-line", then its status should be updated. Hence, if you don't have any other warning or error messages, then this process is normal.
This Frequently Asked Question applies to all supported releases of ESP Workload Manager beginning with 5.3.