The timing is sus, but let's all remember that he already asked the Shadows to look into Count Illuminity back in chapter 26, so he wasn't specifically doubting Ran in this chapter. Plus, back in chapter 26 he was generally more wary anyways. He's just reaping the rewards from planning waaaay in advance from back then; the timing of additional information was pretty good for him. He's also not looking into RAN, he was looking into the COUNT. That probably doesn't amount to much, though, since he knows that Ran by herself can't do much - the duchy resources are hers temporarily and are pretty transparent to everyone, and she doesn't have any specific group of people under her that aren't also loyal to Lachia and thus Yus.
Plus, if anyone were in that situation, I'd think Ran was acting suspicious too. I'd like to know rather than not know what's going on if there were the means.