Hi!
Nothing to worry; that is just normal oxidised pee. Pee usually discolours when in contact with air; the more longer it is exposed. Any even rusty/orangey spot is nothing to worry about. If left for longer, the outside ring around the puddle will dry in a darker shade but in the same tone.
Blood doesn't have the same specific weight as urine and doesn't mix evenly with it; you either notice it as small red spots in a pee puddle or as a red ring around the urine patch if there is a lot of blood in the pee.
The typical very intensely red pees at the onset of a urinary tract infection or cystitis are actually phorphyrine and not blood; blood can be present in quite large quantities in clear or discoloured urine. But you certainly want to see a vet if you come across them, especially if your piggy is squeaking when peeing or pooing.
Any fresh blood coming from the genitals should be vet checked within a day. There is always a serious cause.
I hope that this helps you?