Should I ask my boss?

I started a new construction job 11weeks ago with a fantastic company who do lots of hours, pay double overtime rates and do everything by the books. My workmates are fantastic, to sum it up I really love my job. I show this by working hard both and paying particular attention to detail in my performance, I'm only a casual employee ATM doing 56hrs per week.

Problem- the company has started letting people go. On Wednesday two full time employees (doing the same role as me) were given two weeks notice one is pretty hopeless but has been at job for 2years and the 2nd has been employed for 6months.

On Friday a young fella same role as me was told the same thing, he has only been here as a casual for around 6weeks but he's a good work and well liked.

My problem is I haven't been told anything, the foreman and supervisors say hello everyday and were friendly to chat. As a casual employee who's hoping to be given the full time contract it's a bit worrying watching the people around me be let go... I've been told by others I'm safe but unless I hear it from the boss that info means nothing.

Should I approach my boss or keep my head down and keep working?