I'm getting concerned about a beer I made last Thursday. I pitched with Gervin yeast that had been re-hydrated at 35°C, after reading an article linked from this forum. After nearly four days at a constant 19°C, there has been no airlock activity at all and then lid of the FV isn't even domed. Out of panic I did take a sneaky peak under the lid and there is a thin head (~1/4") of yeast on top, but I can put it down to one of two possibilities.
First, the yeast was harmed by the temperature of the re-hydrating water, or
Second, the yeast is working normally, but the seal is not quite airtight. (I had an issue when removing the airlock from the grommet after the previous brew in that FV and by using BF&I, eventually managed to pull it out, dragging the grommet out with it.)
I have ordered a new grommet to replace the suspect one before the next brew, but believe that this situation shouldn't adversely affect this beer (I have read that many members don't use an airlock), but I have also got a spare packet of yeast at the ready, just in case. I am wary of opening unnescessarily, even to take a gravity reading, but how long should I wait before checking and if necessary re-pitching?