Adoption of 6 week old kitten

We are about to pick up a 6 week old kitten at a local veterinary. When I turned him on his back to cuddle him (like a baby), he freaked out, heart beating rapidly. He didn't appear to like to be held (at least at that moment), but when he is on the floor in his cage, he runs around it happily with his siblings and plays with your fingers when you put them under the door and seems to like the contact with you, albeit through the glass. Is there something I should worry about.. or is there a chance that this kitten will mellow out as it grows and not be afraid to be held right side up or cradled like a baby? With my last kitten that young, she had no issue with being held or cuddled and wouldn't struggle to get away like this one did.

I haven't had cats in a long time, but I think 6 weeks may be a bit young to be taking the kitten. I don't think this behaviour is terrible, at this age he's probably used to being pinned by the littermates and it's a big game, not a soothing tummy rub.

Hi abbytreasures and welcome to the forum !

I have to ask, will this be your first ever kitten?

I'm asking because you appear surprised when presented with perfectly normal kitten behaviour/interaction with strange humans, and, because you're offering your fingers to said kitten. If you go on to adopt this little one, you'd be well advised to cease and desist from that!

Dog Dancer's point about 'early' adoptions is one to be heeded. These little ones need as much time as can be given to spend with mom and their siblings...in North America (I suspect you're in the UK) there's a general rule-of-thumb of eight weeks minimum before separating them....yes, it can be done earlier, but, there may be consequences. Those generally come in the form of (what's perceived as) unsocial behaviour - misbehaviour. That comes about because they've been deprived of social etiquette training, which is naturally 'delivered' by mom and siblings.

Many cats dislike being held like a baby. Being held upside down with no purchase for their paws, especially by a complete stranger, makes them feel very vulnerable and unsafe. Those same cats most likely are very happy to be held properly (upright) or just be petted.
I agree with other posters here about concern over the age of the kitten. I have a cat we strongly suspect was taken from her mom too early. She has no control over her claws while playing, swats people to get attention and didn't know how to play when she arrived. Our other cats, who left their moms later, velvet their claws while playing (although accidents do happen), play appropriately, and request attention verbally.

Welcome to the forum!

I also agree with the other posters about the adoption age.
In terms of cuddling, In my experience, not all cats like to be cuddled, ....but keep on trying as sometimes human persistence (after trust is established) can wear them down.