Concern about the battery percentage shown on mac

Hello. So, I just recently got the new MacBook pro with m1 pro for about 5 weeks now. One time, I was charging my laptop and using it at the same time, so I immediately saw when the MagSafe charger became a green light from my peripheral view. Then, immediately after seeing it turned green, I went to check the battery percentage of the laptop and saw that it was still 98% (it also said 14 mins until fully charged) even though the MagSafe charger just turned green. Then after about a minute I went to check the battery percentage again and it's now 100%. Was my laptop just late at showing the real battery percentage or is this a problem? I am worried since I just got the laptop and it was expensive. The power/ battery condition is normal in the system information.