Thank you for all the responses. It sounds to me as if it gets worse
or if it is really a problem, call somebody in to take a look at it.

I'm pretty sure that the previous owners had a waterbed on the side of
the house that is un-even, so that might be what happened. But, it is
an older house (about 65 years old), and I know that these things
happen. But as for the i-beam, yes, it is a steel one that runs the
length of the house and has two steel columns/poles to support it in
the middle.

Thank you again for all the responses!