Unless you analyse the compiled assembler listing you don't always know how high-level commands affect the hardware. If you've got such commands, it's always a good idea to initialise the ports and registers that you need to use (in your case TRISC and RCSTA) immediately prior to your use for another purpose. That way there's no possbile error or interaction from pervious command usage. But don't forget to set them the way they were prior to using HSERIN/OUT again as those commands may well assume that the registers are in the same state they left them last. This is just good housekeeping practice.