Sandie is right, your cat may be a little sore for a couple of days, but if it doesn't get better soon, or seems to worsen, then check with the vet, just in case.
For future reference, it might be a real good idea to ask the vet if he follows 4-sided vaccination protocol, and get him to explain it to you in detail. The gist of it is that the rabies goes on the right rear limb - R(abies) = R(ight). The leukemia vaccination goes on the left rear limb - L(eukemia) = L(eft). The parvo, herpes and calici vaccines go on the right shoulder and all other vaccines are normally administered at the left shoulder.
This protocol was set up by the American Association of Feline Practicioners and the Academy of Feline Medicine and was adopted by the Vaccine-Associated Feline Sarcoma Task Force in order to help identify and isolate those vaccines which caused sarcoma in some cats.
If your vet doesn't know about it, then you might suggest that he do a little research about it.
Best of luck,