Apple Pencil 1 weird charging issue

Got the Apple Pencil 1 a couple of days back. It was 100% charged out of the box, but drained very quickly to 60% (maybe only after 1-2 hours of use), but afterwards it drained normally as I was able to use it for hours until reaching 30%. Figured this was normal since it was my first time using it out of the box.

I decided to charge it with the included adapter, but it won’t charge at first. I tried charging it using the lightning port on my iPad and it charged. Decided to use the adapter again, and this time it worked. I stopped charging at 90%.

I used it afterwards but I noticed that instead of discharging, the battery of the pencil is actually increasing even when not plugged. It stopped at 97% and doesn’t seem to have gone down since then even after an hour of use.

Should I be worried now? Or should I observe it for a couple more charges?