Yeah, by the time it comes up to pressure, it should be ready. Use a thermapen/meat thermometer to be sure, if you have such a thing.
You’re only reheating it, not cooking a raw pudding, right? So the aim is simply to make sure it’s hot all the way through.
You could do it in the oven but you risk drying it out.
Eta: crossposted with sparklyfish, but I agree with everything they say.