WordPress deleted un-expired transient after post editing

I set up some transients (expired in 1 day) to save query results on a custom post type (e.g Class). Then, if I go to update any kind of post or user profile, my transients was cleared.

My question is how can I prevent that behavior? I just want to clear them if and only if I’ve updated a Class post (using the hook publish_post) or they was expired.

Thanks for your help.