I had that happen to a couple of mine and they both eventually flew off...one time into the water...lucky not to far and not to deep and I was able to retrieve it

Hi,
Sometime it happens!
Often it is when you practice on a mat due to vibrations.

You must verify if the iron head is loose. If it is the case, do not use it and have it repair.
If it is the ferrule, no problem to play with it except for visual at address.

Ferrule do not seem loose because the shaft is tapper.
To repair this, the club fitter has to unglue the head, install a new ferrule and glue the head.

Best regards,

I had that happen one of my 716 AP1's. It is best to take it to a golf club repair to check out. It might be just the ferrule. My 6 iron had to be re-epoxied, the club head was twisted on the shaft.

Grab the head and shaft and twist hard. If you hear any sound the head is loose and needs to be removed cleaned and re glued. If it's just the plastic ferrule, heat it up with a hairdryer or a heat gun slowly while rotating the shaft. You don't need to get it so hot you can't touch it with bare fingers. Then, you can usually twist the ferrule with your fingers or a microfiber cloth. Then, put epoxy or even super glue in the gap and pull the ferrule back into place while it's still warm. Wipe off excess glue and you are good to after it sets.