Hmmm…If you are spinning your tires in an Outback, then I am going to guess that this is one of the Subarus that came from the factory with Bridgestone RE-92 tires. If I am correct about your car being equippe with those tires, I can tell you that those tires are essentially USELESS on slippery winter surfaces, and this is just a sample of what you can expect from those dangerous tires in winter conditions.
Even if you don’t want to go as far as I do by mounting a set of Michelin X-Ice winter tires for the colder months, I would advise you to get rid of those RE-92s a.s.a.p. Think about it–if they were spinning at low speed in snow, imagine how they will perform when you hit a patch of black ice at 45 mph. Subaru should be ashamed of itself for equipping most of its cars with those crappy tires, as even an AWD vehicle needs decent tire grip if it is to transmit power properly to the tires.
All of this being said, since the incident took “well under a minute”, it is very unlikely that any damage took place. Prolonged spinning of the tires can lead to overheating the transmission fluid, but that was not likely in such a short amount of time. Additionally, Subarus have a warning light on the dashboard to warn you of overheated transmission fluid. If that light did not illuminate, then it is fairly clear that you did not overheat the trans fluid. However, just to be on the safe side, I would advise that you check the trans fluid for both the presence of a burned smell and/or a brownish color rather than the normal pinkish-red color. (Consult your Owner’s Manual for information on how to check the fluid)
Now, do yourself a HUGE favor and get rid of those Bridgestone RE-92 tires before you have problems more significant than spinning your tires in a parking lot. If you don’t want to invest in winter tires, at least get a set of all-seasons that will handle slippery conditions properly. I recommend the Goodyear Triple-Tread tires, or if you want to spend a bit less money, the B.F. Goodrich Touring T/A tire (sold at Costco!) is a good value and is infinitely superior to the RE-92s in every way.