I wanted you to look at something for me, but I seem to have forgotten it at home. [How careless of him, right?? Gosh!] With the way the weather is, I'd rather not have to make even more trips right now. I'm sure you understand what I'm saying.

[In other words, he could get his help on this mystery thing another time. Of course, there was no mystery thing, but if Izumi followed up on it, he could always come up with something for him to do on the spot. (Like, you know, maybe mow the lawn??)

The excuse probably doesn't help Izumi's impression of him, but Rohan doesn't care too much. He could think what he wanted.]

Anyway, I'm sorry for bothering you at a time like this.