That's what we call frustrated sarcasm. Trust me on this one. I'm an NT girl that's the master of snide, frustrated, acidic sarcasm
She's frustrated by something...something about you...perhaps the time accuracy. I've noticed this as an AS trait particularly in IRC, and it does actually annoy me after a while. We NTs aren't quite so punctual, and can find time punctuality to that degree like being held in a straightjacket
Actually, that remark sounds like something I'd say, word for word.
And I'd only say it if frustrated at that point in time. No offence to the person targeted either, it's a complex way of saying 'stfu' really. She meant no harm, no offence. We NTs can be quite secretive or elusive when it comes to venting frustrations. Yeah, making fun or someone can be a way of venting it...it's also a way of testing the water and seeing what everyone else thought. Had there been signs, eye-rolls etc from the rest of the class, know someone has been outnumbered...note carefully who the eyerolls are in reference to, you or the whining girl. Lol.
Essentially, try not to obsess about doing certain activities. They are for the teacher to decide. Interacting and controlling to heavily in this area will get you labelled as a teacher's pet, which leaves you WIDE open for ass-reaming from everyone else.
Been there done that. Yeah, an NT gal as a teacher's pet. It happens. Learned by the end of primary school to NOT GO THERE. Just chill and go with the flow.
And as far as time goes...unless you're in a clock-in clock-out industry, if you're needed for extra work by a few minutes and you want to walk out and go home because it's finishing time on the dot...expect to get whacked upside the head Time lee-way is a GOOD thing to a degree.