Jessica's world revolves around studying at college and affording prepackaged meals, which leaves little time for socializing. In fact, she is quite content without being noticed, which only makes the attention of a mystery texter all the more unwanted.
She isn't unfamiliar with strange advances, but this is something entirely different. This person knows things about her. Things beyond just an average stalker.
Even after all that, Jessica would be much more content to forget than discover who is chasing her, electronically or otherwise. Eventually, she finds out that she can't outrun her past.