Probably a 'gust front' rather than the 'hook echo' part of a storm

I'm looking at some pictures of storms online.  That horrible looking horseshoe curved thing was probably a gust front.  It DID actually have mammatus clouds under it, though.  I called a radio station to ask them if they had had any tornado warnings earlier, and they said no, it was only a severe thunderstorm warning.  This is sort of disappointing, but yet, in the big scheme of things, I should be happy that I was probably NOT right underneath a developing tornado.