Ok - that's really poor opsec. If I'm going to the bathroom in a train with my laptop (whether it's expensive or not - it has access to all my stuff - which is arguably more valuable), I'll sleep it, put it in my backpack and take the backpack to the bathroom with me.

My work policies state you simply cannot leave your laptop out of sight for any period unless it's in a secure location (work|home). I feel the same way for my personal laptop as well.