It's like the feeling you get when you have second thoughts or second guess yourself. Not really suspicious, but more with a self reflection/introspection tone.
As I thought more about what she said, I began to feel ___. Why didn't I catch her cues the first time? When I ran over the speech again, I felt ___. Why was it so difficult for me to accept what he wrote? Also, what are some verbal cues that can describe this feeling?
Here are two suggestions that seem to fit into your context. “I began to feel uneasy ... I felt disquieted”.
If the last sentence is part of your question and means that you are looking for verbal cues, you might listen for phrases containing “anxious“, “concerned”, “I wonder ...”, “worried”, “ill-at-ease”. These are all pointers to unease and disquiet in the mind of the speaker.
I do not repeat easily-found dictionary definitions here.
