Confused!

Torrie • Mom hard. Work hard. Wife hard. Repeat.

Ok so this app told me the Aunt Flo was to start today. I told it I didn’t start and now it’s moved my period to start on Tuesday. I haven’t ever been late with this app so I didn’t know that it did this. I took a test on Friday but it was negative. I’m just curious if this has happened to anyone else.