No problem. Just keep a close eye on him for a few days and if there is any odd behaviour, refusing to eat or vomiting, get him to the vet for a check up, because bacterial infections can take a few days to grow and spread.
Tony
Thank you tony,
I have monitored him over night and he seems fine, eating drinking and going to the loo, so think panic is over, thank you for your help :)
The fact it had been frozen means it would have been in reasonable condition and may not have developed the volume of bacteria that old cooked rice can create. Two days is still quite a long time, and of course there may well be bacteria developing, so I would go to the vet - just to be safe. There may have been other "problem agents" in the wormery too. Cooked rice in enough volume can also dehydrate a dog, because the rice will soak up fluid inside your dog's stomach and intestines, so ensure he drinks plenty of fresh water.
Tony