Should I ask my friend if she's okay now?

ealier today i was waiting for my friend after class and she walked out crying silently to herself, and i had NO idea why!! i had just had the whole period with her and i hadn't noticed before.. but i hadn't looked at her during class. i assumed it was because she felt behind in that class because she had been absent for 2 days before an the teacher is kinda scary... so the whole walk to the next class i was just trying to say consoling things about how itll be okay... but i dont even know if that was the reason she was crying! now its later tonight and i want to ask if she's okay through skype. what should i say?