I agree with everyone above, I think you are fine and I also don't think you will notice any shorter life of the stock solution. The stock solution starts to go off when there is a lot of air in the bottle ( for me it's usually when the bottle is nearly empty. ) I'm just finishing a bottle now, it's got an inch of dektol left in the bottom, and only the slightest hint of yellow... it works fine. BTW I routinely use dektol at 1:3 ( and develop for 2m 15s instead of 1m 45s ) and sometimes 1:4. I keep a liter bottle of "working solution 1:2" and it keeps very well too as long as there isn't much air.