From the information you have given, you have signed a piece of paper saying that the dog is food aggressive at pick up. However, you have later found that the dog is actually aggressive to your husband when he stroked the dog (not food related).
It could be that the dog just needs time to get to know you and your household. However, I would phone the rehoming centre and say that there have been further issues. I would do this as a causionary thing to ensure that the if you later decide to take him back, then they had been warned.
My friend lost her much loved black Labrador at 12 years old. She got a rescue border collie cross 6 months later. This dog bit her ankles and jumped up and was aggressive when she came into the room. She spent weeks crying at work feeling scared and guilty.
However, she phoned the rescue centre and told them what was going on. They said they would take the dog back but she gave the dog time to settle. Eventually it did settle. But that was a happy story, many rescue dogs don't settle.
If your dog doesn't settle and you take it back. Yes you would have had it longer and it would be more disruption to the dogs life, but truly, the dog probably is not right to be given to any home.