I should preface with saying I'm a beginner rider, so this could very well be a riding skill issue. I want to describe an issue I noticed about my new-to-me 1980 Honda CM400T and see if it's normal or an indication of something that needs adjusting. Guy I bought it from seemed to really know what he was doing, and was/is very willing to help diagnose or even fix mechanical issues as they arise, so that's good.
I notice this issue really in any gear, but it's most noticeable in 1st when riding in slow-moving traffic at ~5mph. While the clutch is fully out, I can move through stop-and-go traffic comfortably by rolling the throttle ever so slightly on or off. Problem is there's definitely a threshold when the bike seems to "grab" (gain a little acceleration quickly and get a little louder) or "let go" (lose a little acceleration quickly). This happens even with careful gentle use of the throttle. There's like a cutoff point on the throttle where this happens, and it's a lot more noticeable at low speeds.
Note: This isn't when letting off the clutch, so I don't believe this is an issue with letting that out too fast. The clutch is fully out while this is happening.
Note: This also isn't only in first gear. It just tends to be the most dramatic in first gear when riding very slow.
Any ideas why this could be happening?