Credentialing Fee

I recently left a practice after 2.5 years for a better opportunity elsewhere. Although my contract with the previous employer states that they will pay for all credentialing and licensing fee without mentioning of pro rata upon termination. My state license was renewed a few months before my departure. The practice is now requesting me to pro-rata the license fee for the future period despite my separation from the practice. Is this legal? It seems so petty!
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: Ophthalmology: Eye Physicians & Surgeons Source Type: forums