A "pressure canner" and a "pressure cooker" *may* be two different things.....in that the canner is often much larger than what you have for using to make dinner in a pressure cooker.
There is a good chance that your tops coming loose was a blessing in disguise because these soups may not have been canned correctly and could have made your collegiate really ill.
Then again, if they *were* canned correctly, there's a good possibility that the jostling and bouncing of the jars during packing and shipping to college was enough to breach the seal on the lids. That, too, would make them inedible so they'd cause some serious gastro-intestinal illness.
Never play around with home canning! Always check with your local Home Extension Service for correct methods. Improperly canned foods can be deadly. Seriously.
Jan in VA