I agree with DeSense on the new trousers. You should keep them. They look slim enough to me... And for summer pants, as noted, a little bit of space is a good thing.
I am still curious what the difference is in width. 0.25 inches? Is it the case that the flannels were cut slimmer than the published specs?
Alas that Jamison isn't here to weigh in on these differences.
I'm leaning towards keeping them—i'll measure the exact difference tonight. It's like a half inch, which would be a full inch difference in circumference. Within my tolerances—though probably not within manufacturing tolerances.