Why is the alarm going off when it wasn't set?

[AC Question]

I am at a sleepover with my friend and at 7:36 an alarm went off. It wasn't a scary alarm (it was like good morning good morning have a very good morning) but we've spent ages looking through her phone and we can't find anything which would have triggered the alarm and now we are scared. What is wrong with her phone?

 

[B. Diddy]

Welcome to Android Central! Did it only happen that one time, or has it recurred?