Statistically speaking insanely improbable. ~5m people and thousands of Americans visit Iran every year. Unless you're a anti-govt journalist or intelligence related you have nothing to worry about.

N.B. the argument that Iran will falsely label you a 'spy' feels weak to me given the order of magnitude of such detentions in recent history is in the tens. It would be equally improbably that most of these detentions were false positives as plenty of foreign intelligence operations happen in any country. Especially given the amount of foreign-intelligence related sabotage in recent Iranian history.