This is a known issue for a small number of EX4500's that were shipped without the default factory setting of 'virtual-chassis' and jloader. Both are easily corrected (See PSN for details) and non-impacting.
A small amount of ex-4500s have been shipped without the standard factory default PIC settings. The default setting of pic-mode should be 'virtual-chassis' yet they are configured as 'interconnect'. In addition, these units were shipped with a jloader package which the system detects and generates a warning message upon login.
Please let me know if this resolves the issue.
Making those changes appears to have fixed that message.