Puppy Resource guarding

My 4 month old male Field Golden Retriever is resourceful guarding. From what I’ve seen in comparison it’s quite mild, he ONLY resource guards high value treats (like frozen pupsickle, frozen peanut butter treats, anything that takes awhile to get to that he can also eat) he doesn’t resource guard bully sticks, or chew toys. I can pet him and take them and he doesn’t care at all. His food is a little weird, he doesn’t growl often with his food but he does tense up a lot and sometimes freeze or try and eat it as fast as possible. The weird part is, both with high value treats and food, he doesn’t care if you grab the treat or food, he can watch you walk up and take it and he won’t tense up or growl 90% of the time, it’s only when I touch HIM does he growl and tense up. If I pet his head or back, even gently, while he’s chewing his treat or eating his food he tenses up a lot and growls a lot with his treat. Things I’ve tried so far: when I first noticed it obviously I thought it was a control thing so I made sure to lightly grab his flank and take the treat away, trying to enforce the idea that he doesn’t control it. I’ve sense read up on it and heard that might not be the best way to go about it. Right now I’m feeding him by hand, and when he has a treat I will make sure everytime I walk up to him i offer him another treat of equal or higher value like a training treat, and take the one he has for maybe 10 seconds, pet him and give it back I’ve only just started this so he still growls when I pet him while he has it but not once I’ve taken it. He’s only tried to bite me a few times and that was when I first got him at 10 weeks and the resource guarding was worse especially with food. Now he rarely shows teeth and normally just a low growl and tenses up. I don’t want this to become a worse problem. He’s great in every other area, crate trained, potty trained, loves other dogs and people, place trained, super smart dog.