writer.at.heart415,
It was obvious that he caught that I didn’t answer the question, and I feel terrible for my reaction. I know that I should have just lied and said yes and dealt with the consequences whenever they would arise in the future, but I wasn’t thinking on my feet and now I just feel really bad.
I think your sensitivity to the campus rabbi’s feelings is a wonderful thing. My guess is that he wasn’t particularly offended; after all, his job on the campus is to assist a diverse body of Jewish students, not to get emotional reassurance that every student trusts his kashrus and would eat in his home. You stated clearly that you don’t eat in other people’s homes without knowing their specific standards, and he should respect that, even if he thinks it is strange.
If you are still worried about having caused him offense, and assuming that you are planning to largely forgo eating food cooked at anyone’s homes near campus (but are ok with eating food you know to be kosher in their homes), you can perhaps say something like, “I’m sorry I didn’t answer you before, it was hard at that moment to fully describe how I handle kashrus away from home. I would love to eat at your home, but to avoid offending anyone who may have kashrus standards that I am not comfortable with, I have a policy with everyone who I am not closely familiar with, even those who’s standards I would probably trust, to only eat foods that are brought in from an outside kosher establishment with [insert local hashgacha you trust, if any] and are not reheated (or reheated double wrapped). I really appreciate your invitation, but totally understand if my policy is too much of a challenge on short notice. I can bring something too, if that would be helpful…” That way, you can avoid eating at his home (or perhaps eat something there that you feel comfortable eating) without telling him that you don’t trust his kashrus, and also without fibbing that you trust it, but then have to make excuses every time you get an invitation.