I think it's great! I'm in my 30s and going back to school for something I've always enjoyed doing, photography. I have similar fears regarding the age thing. I'll be competing with people in their early to mid 20s and have to start at the bottom by being an assistant to someone close to my age.

You bring something to the table that the younger people don't have, experience, calm demeanor and more confidence in your ability. Also, more likely to stick with a company instead of hopping about every couple of years.

Go for it and keep believing in yourself.