New transom went from a 16 degree to 13.5

[real deal]

So I poured my transom with arjay and it went well but as I’m finishing the fairing and pulled out the carpenters square for one last check before ordering my bracket I got a measurement of 3.5 and before it was 4” kinda weird, thinking maybe the heavy motor pulling on the week transom gave me a incorrect reading ,however I’ve read that the 20’ has a 16 degree transom. Any insight would be great .