In general, how safe is it to travel (to Canada) once I've received my EAD for a green card through marriage (to an American citizen). I entered the US on a TN

In general, how safe is it to travel (to Canada) once I've received my EAD for a green card through marriage (to an American citizen). I entered the US on a TN visa. Do you know of cases where parolees have been rejected at the border upon return (assuming a short 2-3 week trip)?