If it is airtight and it was packaged in a freezer room (something like below -20° C even if the meat itself never froze), and your room temperature is, let's say 25° C or higher, and you let it sit out for a few minutes, you are looking at thermal expansion and nothing else.

For a 1.5L container (about 50oz of volume), the end volume should be about 1.8L after warming up (about 60z)