Found a lump on my cats neck in between his shoulder blades

I was just stroking my 14 week old kitten and I noticed a small, hard yet slightly squashy, moveable, disc like lump on the back of his neck in between his shoulder blades the exact same place he had his first injection he had his injection about a week or so ago I was just wondering if this is normal he lets me touch his neck and he's still very playfull not tired or aggravated at all and shows no sign of being in pain please let me know what you think

It may just be a reaction to the vaccination.  Keep an eye on it for sure and see if it dissipates.  It should gradually disappear.  If it's not noticeably smaller in the next week or so you may want to call the vet and see what he/she thinks.  It almost sounds like a fatty tumor.
 

Is it rice-shaped and is he microchipped?  If so, it could be his microchip.
 

Vaccines frequently cause immune reactions, causing a lump. Let the vet know about it the next time you're in. And if it isn't smaller in a week, give the vet a call.

My 15 year old cat had a reaction to a vaccine shot. It was a rabies shot since in Texas, our state law makes it mandatory domestic cats have to have a rabies shot. It too created a lump. A small procedure removed the lump and the vet made sure that particular vaccine isn't used on my cat.

There are two types of rabies shots my vet uses. A three year one which she told me has "additives" in it and a one year shot which has "no additives". The three shot is the one which caused the lump in my cat. My cat now gets the "one year shot" and has been getting this yearly shot for the last four years. No reactions.