Don't forget that if this was a PA gig, depending on the style and the FOH, the house may be compressing the final PA mix in a big enough way to cause waveforms like that -- after all you're just recording what's coming out of the house. I've personally recorded shows that looked like that. If it sounds OK, and the limiter was off, and you don't see clipped peaks when zoomed way in, then I bet it just sounded like that.