Ritalin can cause temporary movement disorders such as akathesia (which can be treated with a side effect pill). However on occassion it can also cause some long term movement disorders which include at times tardive dyskinesia (and a variant of it called tardive tourretism) for more information google "Patient Education Tardive Dyskinesia" (as the site itself says "some of these medications may be medically neccessary"). As for for the risk/benefit analysis considering that its helping you it might be worth it but if your psychiatrist has concerns they are valid so discuss this further with them.
My son is 7 and has been on Concerta for over a year now. He started with 18MG which worked great. No side effects and had a wonderful experience at school. This year his dosage was increased to 27MG and now I've started to notice a tic I guess is what you call it. I was searching the web and came across other post because I was wondering if it had something to do with his medication. His tic is he wiggles his fingers, he does it and he doesn't even realize it. At first I thought it was just something he was doing like a kid thing but after reading all the post I think it's related to the medication. It does't affect his day to day activities like writing or playing video games and so on so I'm not sure what to do and I'm wondering if it will progress into something worse?
The increase may be too much for him. It is definitely something you should bring up with the doctor.