You can't just inflate and deflate the tire and hope that it's correctly installed. You have to check. Check that the bead is seated the same all the way around. Most tires have a molded-in line near the bead that you can use to check. Just look around the tire and see if it's a consistent distance from the rim. Check both sides. If there's a low spot where the tire is too far in the rim, squeeze the beads together around the rest of the tire and pull the low spot outwards. If there's a high spot check that the tube isn't pinched between the tire and rim (see next paragraph) and pull the tire out around the rest of the wheel.

You also need to check to make sure that the tube isn't pinched under the bead. You do that by deflating the tire, and starting at the valve, pull the tire to one side and look between the tire and rim. If you see tube or don't see rim strip something is wrong. Work your way around the tire checking both sides I do this before inflating. It only takes 30 seconds.

As far as the rim goes, rolling off a 1.5 in drop probably didn't cause it to go out of true. Wheels tend to go out of true easier once they have been out of true. And rims that are out enough to require significant compensation in spoke tension also tend to go out of true easier because of the uneven spoke tension. It's probably been going out of true for a while.