How long a run are we talking about? Could be as much work to reinforce as to sort it properly, and it could end up looking a mess. OCD would get me with that one. I would have to get it sorted.
You say no lambs this year but certainly for next years lambing I would want it corrected, it would be on this Spring's list before the grass gets too high. Also, I've seen young fox cubs easily get through small holes you would think nothing could fit through, so I wouldn't risk larger gaps with newborns lambs out there. Plus, if a lamb did get through mum will have the lot down in her desperation to reach her baby.
A few years back the chap putting our fence up just got to the end of his 2nd 50m run when I went out to check and spotted it was upside down. Cue much moaning when I made him remove it and refix it the right way up.