Please tell me I didn't damage my transmission

Was out driving last night, and came to an intersection that was kind of uphill right where you stop, for maybe 20-30 feet. I had this great (not great) idea to throw the car into SS mode and put it in 2nd because I like the growl my intake makes when I take off in 2nd gear.

Anyway, light turns green, start going, feel jerk, 2nd gear starts flashing, car automatically went to third, and by this time I was going like 25-30 mph, speed limit is 40. Shifted to 3rd, 4th, and 5th normally, so I decided to slow down (this was late night so road was empty). I slowed down to 30 and tried to shift to 2nd, and it just flashed and stayed in 3rd.

I turned on a side road, came to a complete stop, and voila, problem somehow randomly solved. Tried to see if it would come back and nothing. Shifts fine in SS mode, shifts fine in auto, no jerk, everything is smooth sailing. So wtf did do?

I'm not gonna lie that it was stupid to start uphill in 2nd gear, but we all do stupid things from time to time haha. I've taken off in 2nd before (for the growl!), and everything's been fine. I did check the oil this morning and it was halfway between the markers so I added like 1/3 of a quart ATF. Took it for a spin again, even gunned it, and it was all good.

Did I screw something up, or was that just bad timing or wasn't giving the car enough gas while going uphill for like 30 feet?

Pretty sure I'm freaking out over nothing, but I remember the horror stories when I had my TL that had me biting my nails every time I drove that car.