ICSP design problem on PIC16F628A
If you try to pull more current from the ICSP than it's rated to supply, you could damage the ICSP, or trip the breaker in the USB hub (if you have a decent hub with proper breakers).

It's reasonable to assume that an NPN transistor will not turn on spontaneously.  It can turn on from the I/O pin.   If you wish to be extra safe, you can add a fuse to the +5V line in the ICSP cable.

Few more comments on your schematic.


Did you deliberately not add a 47kΩ pull-up between MCLR# and +5V ?
Schottky would be a better diode for back EMF protection of the relay.