Past tense

I can't believe the day has come!  As we were driving in the car today after taking naps at the office, (the kids, not me) Macy spotted a school bus and screamed out "BUS!"  We went to the post office, then were back on the road in which she spotted the bus.  She said, "Macy see, Macy saw a bus."  She corrected herself and used the past tense!  I sat in amazement.  Anytime she or Connor would say they see something that they already saw, I would say "You saw ____". She picked up on it and did it herself today!  

Part of me is thrilled this is something she might be catching onto.  However, another part is SO sad.  One more step to adulthood.  (I know that sounds ridiculous because they are 2, but you all know what I'm talking about.)  I am trying to savor EACH and EVERY big or little step.  It seems like I blinked and they are now 2 1/2.  How much more time will pass in my next blink????