Most Helpful Girl
That's quite odd... It could be he is trying to see if you're willing to come to him and talk with him. Maybe he's too unsure about communicating with you, or maybe there's something he wants to talk to you about, he could miss you, or simply wants to checkup how you're doing, etc. It sounds like he stares at you as a way for you to notice him, so he makes himself known to you and gets your attention. He may be seeking if there's any connection left with you both.
That's probably why he went into the nail salon, he noticed you there and chances are he was planning to see if you'd stick around until his appointment was given, if so - it'd be a sign of interest and he may want to talk things over with you. But since he didn't show up, he could be using it as a ploy to get you to message him out of curiosity, or connect with him somehow and initiate contact.