On the subject of paranoia, if I remove the airlock I fold up one square of toilet paper and sellotape that over the grommet to stop anything getting in. I do this when I move the FV at bottling time as when I lift the FV it sucks on the airlock (perhaps that's why they're such good friends) and can draw the liquid in the airlock into the FV, it's boiled water by why take the chance. Once when struck by genius I tried fitting the grommet into the lid when it was on the FV and the yeast had been pitched, the last I saw of it for two weeks was it plunging into the depths of the wort. Resisting the urge to immediately go after it I just sellotaped the folded square of toilet paper over the hole and left there for a fortnight and it was great. Any excess CO2 could get out but no nasties could get in, result!!