Hi Matt,
Welcome to the forum. There are good reasons why not to release a snake that has been in captivity. They still retain their sense of smell (prey detection) and hunting instinct, but they might pose a risk to local populations. If the snake has been brumating, then it's less likely to have been stressed out by confinement and would be a better candidate for release (if you choose). Since garters disperse in the spring, the odds of an unhealthy snake affecting a lot of other snakes are somewhat lower. Here's a link to the post to which abcat was referring (
Forum Newbie). Best wishes,
Rick