Clutch pedal stuck down yesterday, any ideas?

As we all do from time to time, I stalled the car yesterday. I didn't think I had let the pedal out too quick but hey ho, it stalled regardles. It stopped under a car park barrier though, in a panic to not have it come down on top of my car I rushed getting it going again.

Quick ingitnion ion off, clutch in, change back into first, ignition on, a few revs and let the clutch out. I did not launch the car at all but the whole process was rushed.
Istantly it didn't feel right, pressed the clutch for second and it wouldn't find a gear, I couldn't even grab first again, I then also noticied the pedal was very dense and not retracting fully (to level with the brake pedal).
Itially ly I presumed id shatter the clutch/flywheel. Turned the car off/on again. Managed to get first and drive off like normal. I could change gears fine but the pedal was still dense and sitting low. A mile down the road I managed to get my foot under the pedal and flick it back. It returned to its normal position and since has driven fine. On/off load etc.

my my clutch has never slipped or missed a beat. I don't launch it and its still stock map.
Ive checked that the matt hadn't got caught but that's well clear of the pedal.

Anyone ne got any ideas of what happened? It's never done this in the 15 months I've owned it.

Car is a S3 8P 57 plate one 42,000 miles.

Any reason why it just randomly did it? I didn't know if it was because I was changing gear and pressing the clutch whilst turning the ignition on and off, I.e making its own air lock?

Is there any way I can test it. I'll look to book in for a full brake fluid change and get them to bleed the clutch too.

With then engine on and off today, I pressed the clutch pedal in/out several times with different amounts of force. Tried a steady launch also and the fault will not repeat.
Possible it was just a odd thing?