At four months, while you've got a lot of healing behind you, things haven't completely settled into place. A wise member once told me that the majority of healing takes place in the first six months, with the remainder taking a year.
My guess is that you're getting some food stuck at the wrap site from time to time.
The gas should subside in time. It's a sign that your wrap is working.
It is still (and always) important to eat slowly and chew your food completely. That wrap of yours is doing its job, and because of that it's requiring you to do yours. It's a two way street! We were years getting into the habit of eating fast and not chewing our food completely. It takes time to change that.
You may get a bit of reflux now and then, depending on what you eat. If something gets hung up at the wrap site, it can keep it open enough to let acid through. Some people who've had very successful surgeries, get reflux after eating certain things. At four months, taking Prilosec at night is no big deal. I'm not sure if your surgeon told you, or you read it online, but often we still require some meds...it's just that the symptoms are much less, and we're still far better off than we were before the surgery.
Hang in there, my friend. Things will continue to improve.
Chew, chew, chew that food!