Thanks for the reply.
That appears to be a good way to see if the port was opened initially, but I am not sure how to determine the port state after a few open/closes. Sometimes the line coding changes due to baudrate or DTR, RTS, etc changes.
I am looking for a something to put inside ...
state = USBUART_1_IsLineChanged();
if (state & USBUART_1_LINE_CODING_CHANGED)
// did the port open?
That seems like a good work around.