The supervisor's right - they should return them sooner.
Honestly, nothing drove me more nuts than people being inconsiderate with communal glassware. My lab was excellently equipped, with a more than sufficient supply of glassware for the people working there - if they were kept in circulation, that is. Instead they sat in fridges, freezers, in the back of fumehoods, often unlabelled and far past the point of their contents being important or, in some cases, even known.
It's bad lab practice. Keep stocks of intermediates etc. in cleaned out reagent bottles. Keep small samples in glass vials or other "disposable" glassware. Don't store your NMR tubes or marker pens in glassware (I'm not making these examples up).
Although, thinking back on it, maybe that stuff was only really bugging me because it was the last six months of my PhD and *everything* was bugging me...
I would have been quite annoyed at that. Hell, I even get annoyed when the people near my lab bench have a bunch of glassware (UNLABELED) scattered around and encroaching on my workspace. It's not like we're heating 12M HCl every day, but even if we're using
but then, we're not PhD students