It's rather more than that, I think. Elizabeth is caught off her guard and reacts with a "blush of surprise" before trying to escape. She does indeed yield to her mother's insistence (to E's credit), but the sentence continues by telling us that Elizabeth feels "It would be wisest to get it over as soon and as quietly as possible." I, for one, would be most annoyed if I were expected to wait any longer for the fatuous Mr. Collins to be rejected - LOL

And whose example has taught Elizabeth that Mrs. Bennet can be treated with public disrespect?