Check for a boolean seems to convert to boolean

I'm using a check to see if findFirst actually retrieves data. I always use it like this:

    $question = Questions::findFirst("uuid = '".$question."'");
    if (!$question) {
        return $this->respondWithError('No question was found');
    }

Now, this always worked for me. But today I found that the code above was triggering the error response, even though the question I was fetching existed. I also found out that if I removed the check, everything would work. I then placed a var_dump() after findFirst but before the check and I placed on inside the if-statement. The first one dumped the actual model, the second one dumped a boolean. Anyone have any ideas as to what's going on here?