I had a terrible pen grip as a child, though developed beautiful handwriting, and everyone gave up trying to get me to change and thought it was fine.
Then I ended up in high school/university with loads of pain from writing at top speed in exams. Years later, I have loads of RSI problems, pain, tension in my arms/shoulder, difficulty doing things like musical instruments, etc., and wish that someone had evaluated me properly as a child. Instead of trying to force me into the standard grip, which didn't work (and I ended up with a thumb-wrap style that used a lot of pressure), there are a couple of other acceptable grips that would have been better for me; shoulder exercises and learning to release the tension in my forearms would also have helped hugely.
So a beautiful style of writing doesn't mean there is nothing wrong, and often the pain and difficulty at speed doesn't show up until much later, when it's more difficult to change.
So worth keeping an eye on it.
(by the way, I've now changed my grip to what is known as the "monk's grip", (amongst many other names), where the pen goes between my index and middle finger, and takes the pressure of my thumb).