Oh not meaning to yell AJ - but boy that hit a nerve. As stated in several post - cajun cooking does not use tomatoes while creole does. Just a thing, from below N.O. say around Chalmette to around the New Orleans/river region they do use tomatoes in gumbo as they also make a red Jambalaya. But for Cajuns on the bayou - Bayou Lafourche from Thibodeaux down to Larose going westward to Lafayette area - there is no red in gumbos or jambalaya.
People around here have had fights over this, as no loyal cajun would ever want to hear of, see, or eat a red gumbo or jambalaya. They feel the whole reason of making a roux is to have a brown base and to be able to taste the roux without the red stuff. Sort of nullifies the whole idea of making a pretty brown roux to the darkness you desire then muddling it all up with red stuff. In this area, Red gravies, sauces, and dishes are reserved for Fish Courtbouillon or whatever kind of Sauce Piquante you want to cook. But to each his own - your gumbo still looked good.
Go to this site and there is a little write up about it- but as you can see there is a lot of blending also going on in some areas. In fact look at the receipts, some have the tomatoes in the gumbo but the majority do not. http://www.chefrick.com/cajun-recipes
Take Care and keep on cooking.