Well, it mentions that Gandalf does go back and visits very briefly with Frodo every now and again. But there was a time of about 17 years at the end of the 30 year period that he didn't see him.

Turns out, Gandalf was researching the ring and was returning to check on Frodo to see if he was experiencing syntoms that was consistant with the One Ring, such as stunted aging.

I've just started reading the books again myself. I'm about to the point where they meet Strider at the Prancing Pony.