Hello Cliff,
I suppose there could be solder in some cans, I really don't know. My opinion is that if there is, it will show up in the seasoning process where you would heat the empty cans in the oven to 450F degrees or higher. If ther is evidence of solder after this step I would discard those cans and look for others.
Anyone olse have aexperience or knowledge of solder in coffee cans?
Kix