Is Gilbert concerned for the affects of his assault on Lawrence?

Yes, Gilbert was concerned and unsure about what to do after the assault, but he decides to take his chances by saying and doing nothing.

I ought to have helped him in spite of himself—to have bound up the wound he was unable to staunch, and insisted upon getting him on his horse and seeing him safe home; but, besides my bitter indignation against himself, there was the question what to say to his servants—and what to my own family. Either I should have to acknowledge the deed, which would set me down as a madman, unless I acknowledged the motive too—and that seemed impossible—or I must get up a lie, which seemed equally out of the question—especially as Mr. Lawrence would probably reveal the whole truth, and thereby bring me to tenfold disgrace—unless I were villain enough, presuming on the absence of witnesses, to persist in my own version of the case, and make him out a still greater scoundrel than he was. No; he had only received a cut above the temple, and perhaps a few bruises from the fall, or the hoofs of his own pony: that could not kill him if he lay there half the day; and, if he could not help himself, surely some one would be coming by: it would be impossible that a whole day should pass and no one traverse the road but ourselves. As for what he might choose to say hereafter, I would take my chance about it: if he told lies, I would contradict him; if he told the truth, I would bear it as best I could. I was not obliged to enter into explanations further than I thought proper. Perhaps he might choose to be silent on the subject, for fear of raising inquiries as to the cause of the quarrel, and drawing the public attention to his connection with Mrs. Graham, which, whether for her sake or his own, he seemed so very desirous to conceal.