Yes, this occurrence is completely normal given the circumstances.
While it can be gross to look at, finding maggots in this situation is a standard biological process and does not mean there was anything wrong with your food when you ate it.
How the Maggots Got There
Maggots cannot spontaneously generate out of nothing; they are fly larvae. For them to appear inside a tied plastic bag, one of two things happened:
  • The "Micro-Gap" Entry: Plastic bags tied by hand are rarely completely airtight. Houseflies or blowflies are highly attracted to the strong scent of leftover chicken curry. A fly likely found a microscopic opening where the bag was knotted, crawled inside, laid eggs on the can, and squeezed back out.
  • Prior Exposure: In the brief time the can was sitting open on your counter or table while you were eating, a fly may have landed on the inner rim or leftover residue and laid microscopic eggs unnoticed. Once sealed in the bag, those eggs hatched.
Why You Are Safe
Since you ate the food immediately upon opening the can, you are perfectly safe. Canned foods are sterilized at extremely high temperatures during the manufacturing process, making it impossible for live fly eggs or larvae to exist inside a freshly opened, undamaged can. The flies only targeted the can after it was opened and exposed to the open air.
To help you prevent this from happening again, let me know:
  • Do you have a trash can with a tight-sealing lid?
  • Would you like tips on how to properly rinse or dispose of smelly food cans?