How big was the pinky? And how big around is your snake - when he hasn't just eaten, of course? Or, how wide across the widest part of the head, if that's easier to estimate.

My Pugets looked REALLY fat after eating 3/4 of a large pinky (each). Fat enough that I was pretty concerned and backed down to no more than 1/2 a large pinky per meal. Even at the point I thought they were going to burst after 3/4 pinky, they were still looking for more! So I wouldn't necessarily go by what your snake "tells" you he wants to eat. (Though some folks here do feed to satiation and not have problems, so that may be a species/subspecies or individual personality thing.)

But also... my boys are about a foot long, but from what I've seen it looks to me like Pugets are more slender-bodied than a lot of other garters. They're really maybe just over 1/4" across the widest part of the head, and the widest part of their body is probably not much bigger in diameter. So what a foot-long Puget can eat and what your foot-long garter can eat might be different.

For now, I'd just suggest keeping an eye on your guy to make sure he's digesting OK - producing poo and tummy getting smaller over the next couple days would be the things to watch for. And maybe don't feed him again as soon as you normally would.