I would have it looked at VERY close. The 800s were infamous for breaking crank pins on the PTO side. Do you know how many miles the crank has on it? You mentioned 7000 in a post, but I'm guessing that is overall, not since the crank was rebuilt?
If it was true when it went in, the case is nice and tight, and the pin is in good shape then you have to ask yourself why did it go out of alignment? What condition is your clutch in? Has it been balanced?
When I do a rebuild on an 800 like yours I send the crank to a reputable crank shop and have them completely rebuild it... they will know when they get it apart what needs to be replaced and what doesn't. I have the cases checked to make sure they are a tight fit on the bearings. Then I completely rebuild the clutch and if it hasn't been balanced before have it balanced.
Curious, are any of your motor mounts broken? That happens often when a crank is out of true.
sled_guy