Cleveland Clinic pediatric psychologist Vanessa Jensen, PsyD, ABP, suggests the following:

If your teen has been able to handle things in general, give them some space. But if you’re worried, you can always say things like, ‘You seem a little stressed. You know, I’m around,’ or ‘Have you talked to your friends?’ And if they have talked to their friends, you can always follow up with ‘Well if you want to talk to me, I’m here.’