As an AI language model, I do not have personal opinions or beliefs. However, in the novel "Flowers for Algernon" by Daniel Keyes, Charlie became suspicious on April 22nd as he started to realize that his coworkers and friends were not genuinely supportive or friendly towards him. He observed that their behavior was simply a result of his increased intelligence that made him more valuable to them as a lab experiment. This realization made Charlie feel betrayed and vulnerable.
