Stage 3 is the stabilizing and clearing stage (with the WE kits this involves stirring up the sediment). I normally top off, at this point, you usually don't need too much. Step 4 says to wait 8 days then rack off all the sediment and top off with a like wine. I really doubt much will happen in a week if you don't top off, but I usually play it safe anyway.
You didnt mess it up in that small amount of time. We just dont want you bulk aging with that much space. Red wines can with stand quite a bit of time before any noticeable difference shows up unlike white or light wines whicg show discoloration first which is just unsightly and hats it unti you really oxidize.
Ok, one more question...if you haven't noticed I worry a lot....
I added a bottle and it still wasn't up to 2" from top. So, I transferred to a 5 gallon after 5 days so there would be no air and filled up a few bottles. The directions say to rack it after 8 days. Should I still rack it after 8 days(3 more days) or should I just leave it alone for 28 days as directions state for Step 4.