It’s against policy but don’t beat yourself up about it! I imagine that most of the productive and helpful identifiers on the site who started out (like me) without formal training have been overconfident in giving ID’s at some stage (as I have).
Alternatives to agreeing with a species-level ID: to either “favorite” it or to add an ID at genus level or higher. (If you write “supportive” along with your ID, then it will be clear that you aren’t casting doubt on the species-level ID that was given.) Either way you should get notifications about further ID’s and it will help you learn.