From what you describe I would strongly suspect resource guarding. Common problem in this otherwise wonderful breed. I could be wrong, but that's what it sounds like. Maybe you know all this, but I'll write down some tips for you or anyone else who might search this topic
You say he was chewing something. So probably in his mind your OH was going to steal his treasure. He growled to say that he did not like the situation. Unfortunately his growl/communication was ignored and he went to the next step and bit. Of course completely unacceptable to us, but to him it made perfect sense. Because in the dogs world anything you hold is yours and not even the leader is allowed to steal it without being challenged.
I understand your shock and I agree it is not good that he does not have more bite inhibition. But remember that resource guarding can be fixed if handled correctly. Many cocker owners have dealt with this particular issue
If you can then you should contact a positive trainer/behaviourist to help you because correct handling of this problem can be the difference between a small issue and a serious problem.
Like mentioned before it is actually a good thing that he growled. It lets you know when he feels pressured so you can approach the situation differently before it escalates to biting. Growling is useful information and we should all respect a growl
I know I keep recommending this book, but it is so good! It explains everything you need to understand about resource guarding and how to handle it. It is a short and to the point book, easy to read and very informative. It's called "Mine!", written by Jean Donaldson.
Most important thing to know is that resource guarding is a form of insecurity, the dog is afraid of having things/food stolen away. If we decide to take things away or let the situation escalate into a conflict then the dogs fears will be confirmed and he will think he needs to fight harder next time. But if we, however, show the dog that we are not going to take stuff away, then the need to resource guard will go away and the dog will not do it anymore.
So start training "swap" with high quality rewards. This way you will eventually be able to request an exchange and the dog will give up things willingly because that has been fruitful in the past. You can start by offering something nice and when your dog takes it you take whatever he had and say "swap" or "let go". You can use toys and treats, whatever works, just make sure it's his choice to let go.
You can also prevent this unwanted behaviour developing further by dropping treats near his foodbowl or near him when he is chewing something. Careful not to get too close in the beginning, you want to take it slow to be successful.
There are many things you can do to train away resource guarding, if that's what this is. I am sure some people on here have been through it before and can help.
How old is Dylan btw?