Hey thanks for the welcome!
Yeah, that's what I gathered and makes sense if the brand didn't sell that well relative to the rest of the market. I also think for most brands that did offer a 4x28, it is a bit of an outlier scope. Seems a 4x15/4x20 or 4x32 were to 'go to' for magnification and objective lens size for most entry level rifle applications. The 4x28 is the 'in between' scope but it never really found a niche. Even now, most of the new 4x28 scopes are either compact versions or poor variations of a 4x20.