LTSPICE Bridge Rectifier - Odd Output
I think you should be displaying the differential voltage across V1 since it isn't ground referenced. The output (which is ground referenced) is behaving as expected. I don't think that waveform you are seeing makes sense though.. 

BTW, there is a (possibly hidden) place to add series resistance in V1. Make sure that "Parasitic Properties" Series Resistance is set to 0, and I would suggest checking off "Make this information visible". 

Edit: This simulation behaves similarly when I simulate it, and it's due to the bottom end of the source floating around. If you connect a 100K resistor from the bottom end of the source to ground it does not affect the output voltage but the top of the source looks more like what I think you would expect: