Breva 750 - Loose bolt

Hello, Just re-filling the gearbox on my Breva 750 and nudged a bolt (upper left on the gearbox). It has 8.8 embossed on the head. Surprisingly, I found I could turn this bolt with my fingers, and it made a slight grating noise as I did so. Is this right? What’s its purpose? Many thanks, Mike.

8.8 means it is high tensile steel is all. But I would therefore expect it to be load bearing in some way - certainly not finger tight.

Thanks for the replies gents.