Why was Leon suspicious of Luis?

Luis gave him so much valuable information. How to find Ashley and that they saw a group taking a girl into an old church. If it wasn't for him, he wouldn't have found her. This doesn't sound like a man that would betray or deceive Leon. Also, how did Hunnigan know it was the correct Luis Serra? That's quite a common name. I work in I.T and I would need a lot more than just a name such as a photo, age, or a description of what he looks like. I also have a relative who used to work for the government and he said the exact same thing.

I'm not saying that I don't like the new Luis. He is still funny, but I do miss the old bromance that they used to have.