Yeah, that's probably true.
ETA:
Now that you mention it, the response to the Watergate incident was probably as close as we've come to a coup in modern USian history. Even then, the efforts were legal.
But, it was a group of political leaders moving against the legitimate government.
Again, they were backed up by actual legal mechanisms, so it still wasn't an ACTUAL coup. And Nixon's resignation removed any need for one.
ETA2:
Or, if we're going to adopt Trump's usage, the impeachment of Clinton was also a coup.
Not really. I think a lot of people believed the president was a crook after more information came out about Watergate. It was really hard to be a partisan supporter of someone you believed was a crook. At least that's how I remembered it being a young teen living in a Nixon supporting household.