What is the smell of a glass of water in contact with fresh air?
I do have a very similar experience! What the OP calls the mollusk smell, I call it slightly rotting "seaweedy" smell. It has been a very unpleasant experience for us in our new home.  

Similar to OP's experience, this seems to be more intense with glasses and ceramics right after the newly washed dishes get exposed to air when the windows are open. But I also detect it with plastic cups as noted below.

In order to eliminate other variables such as dishwasher problems and tap water quality, I bought bottled water and disposable plastic cups. I did the following experiment.    

WITH CLOSED WINDOWS

Water from bottle poured in a previously unused plastic cup, sitting for 15 minutes : No smell

Water from bottle poured in a cup and couple of sips taken, sitting for for 15 minutes : No smell

WITH OPEN WINDOWS

Water from bottle in a previously unused plastic cup, sitting for 15 minutes : No smell

Water from bottle in a cup and couple of sips taken, sitting for 5 minutes : Seaweedy smell

So I'm about to conclude that something in the outside air combines with the saliva (and/or chemicals/enyzmes from the detergents) to produce the seeweedy smell! The same thing happens with the newly washed dishes out of the dishwasher, and hand washed dishes after they get exposed to air with the windows open.

Yes, I know this doesn't make any sense to people that haven't experienced it before! It sounds like nonsense, but it's quite annoying every time I take sips from water cup. 

I'm almost on the verge of calling up the EPA about it. There must be something in the air, but what...