Anything less than or equal to G/29 does not require you to record moves, according to USCF. Otherwise known as Blitz and Quick, they have a separate rating for those time controls.
Reference: An Introduction to
USCF-Rated Tournaments [PDF]
So, yes, you do need to record your moves in a G/30, because that is considered Standard time control.
There is a rule that allows you to stop recording once you (or your opponent) have less than 5 minutes on the clock, in Standard time control games. See #7: USCF - FIDE Rule Differences - 2 Columns
Additionally, if you have an increment of 30 seconds or more, it looks like you have to record moves regardless of the time left on the clock. (I wonder if people really have that sort of increment in tournaments.)