did I oxidize my beer?

Did you store your racking cane inside your autosiphon? If so, that is why you experienced air uptake. The rubber knob shrinks when constricted.

 

It's normal if you use it a bunch of times, break it and return it to the store with a receipt.

 

I think an auto syphon is another opportunity to complicate an otherwise simple procedure and more to clean.
Take a shot of Wild Turkey rinse it around your moth before you swallow and start the syphon the old fashioned way..

I use a racking cane at both ends. The bottom one makes it easier to get the flowing beer to the keg bottom with much less turbulence.

 

edit:
Take a shot of Wild Turkey and rinse it around your mouth before you swallow and start the syphon the old fashioned way..

 

That's definitely not normal, but it probably introduces air only during the priming stroke. But, you should not keep that sucker. Take it back to your store at your first opportunity and get another one. If your drive does not make it cost efficient (these things are only like 12 bucks, right?) then you need to weigh the cost of an online order, shipping, etc.