[Rivevos Ephraim 5:11](http://hebrewbooks.org/pdfpager.aspx?req=1086&st=&pgnum=43) writes that in Sefer Halichos V'Hanahagos page 59 (Rav Eliyashiv) was Makpid to cover drinks. He brings a story were he covered his drink when he left the room for a second even with someone else there. He also brings a story which happened on Purim where he left room then came back and said don't drink the wine because it was left uncovered .see it inside.