I went back in my late 30's and it was the best move I made in my life, and not just because it helped me with a significant career change.
First off, after figuring out the grad school chicks were pretty out there, I started meeting undergrads. I, too, was worried about the age difference. I was shocked that it didn't weigh in that much, though I look a lot younger than I am.
It was an eye-opener for me as I was an AFC and convinced I couldn't date younger women. Wrong-o. One thing about undergrad college girls as opposed to young women working at the same age, they're much more open-minded about things.
One key was I discovered sosuave.com while in grad school. I started carrying myself differently. Some gals were nearly half my age, but it didn't matter as long as I took care of myself, acted confident, and didn't act older or tried to act their age. I was just myself.
Your early 30's in grad school? Wow, give us field reports, please! You'll be scoring with young undergrads in no time if you play your cards right -- and I'm 100 percent serious.
Some of my rules as noted:
1. Always approach, whether they're 18, 19, 20, 21, 22 and on up. Do not be obsessed with age. First gal I dated in grad school was way too young for me (an international student from Japan), so young I didn't ask her how old. She later told me her 20th birthday was coming up. Don't ask, don't tell.
2. Some gals will let age get in the way, don't get bummed about it, they have legitimate reasons. One gal I asked out was shocked and didn't see me in that light. I really liked her, oh well, she sees me as a big brother today ... I moved on from her. Get "next" into your vocabulary. For every gal that turns you down, another one will accept you.
3. Don't party like a 20-year old frat rat, but also don't ratchet it down so much that you're boring. One time I came home and there were a bunch of voice messages on my machine at 2 a.m., grad school gals I knew (but they were 24 years old), they were drunk and said, "Hey Timmy, we're over here drunk and naked, get your ass over here." They weren't naked I later found out, but were very drunk ... I thought to myself, this kind of stuff was not happening when I was a career man. Enjoy it while it lasts.
4. As longs as you're fun and light-hearted, women of all ages will quickly look past the age thing. Always be fun and light-hearted.
Have fun ... I'm envious!