list of Poisionous House Plants, or anywhere else in their database, (which exceeds 700 plants). The Lily's that are listed, (Spathophylum is related), all show "causes mild irration and swelling".
Now before someone jusmps my ass and shouts, "you don't care", lets say this is for "people" and that often what is bad for people is worse for pets, (that works the other way as well though). And, of course, volume means alot as well.
If Spathophylum is poisionous then I would suspect you would have seen some effects by this time. I'd keep watching for signs of distress but I doubt you have a problem.
Steve