Sounds like it's one of the rail clips that broke on the regulator track. This would allow the window to cock just a little bit and bind in the window guides. You're lucky it's up. I would keep it up until you are ready to fix it or there is a good possibility that it will get stuck in the down position like mine did. If it is going up and down with no problem then you are getting extremely lucky. Your luck will run out soon though.

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2010 Lexus RX350 still new
2003 BMW X5 3.0i w/sport package w/68K miles. (gone Thank God!)
2002 Dodge Ram 2500 4X4 cummins diesel w/198K miles, custom repo truck
2009 Scion tC w/46K miles
2007 Suzuki SV650 custom streetfighter
2000 Lexus GS400 w/165K miles