FG 1.019 does seem quite high IMO, if your OG was truly 1.049 and with US-05. This yeast usually eats much more sugar than most other yeasts, to the tune of ~80% attenuation or more on average.
How are you measuring final gravity? Using a refractometer, or a hydrometer? This could be an issue.
The brand of DME might have hurt the final gravity a bit, but I wouldn't think THIS much. What brands did you use, out of curiosity?
And did you in fact mash or steep at 156 F? This too could have hurt a bit, but not THIS much either.
But if you have a combination of several of these factors coming into play all at the same time, your result is possible.
I wouldn't repitch. I don't believe the yeast is the problem. At least, not yet.