Massive loss of pressure in my front tire but it still holds air Last night I was riding into a parking garage with a steep decline before the entrance. I hit the bottom of the ramp hard and lost most of the tire pressure in my front tire in a split second. I thought it was a pinch flat or blowout right away so I walked it over to a local bike shop where they had a air hose and was able to air up the tire which held the air and is still inflated to the proper pressure this morning. Does anyone know what may have caused the air loss and subsequent flat?

It is a road bike with racing tires and presta valves. I also check the pressure and fill the tires every couple of days so it wasn't flat already.
A tube is a sealed system.  If the rubber isn't punctured and the valve is closed, there isn't anywhere that air could have gone all at once like that.  The only thing I can think of is maybe you do have a small blowout tire side, and somehow the tube is sitting flush against the tire in such a way that it's holding it closed for now.  May be worth taking the tire off and checking the tube itself, being prepared to replace it.  Because(in the one in a billion chance that this is what happened), if that did happen, it could be hazardous to keep riding on it.