I agree, we have a few with limps at the moment but would not distress them by catching them and doing anything with them at the mo until they have actually lambed.
If they are literally hopping then ,maybe have a gander, but limping is just a sign of mild discomfort. As long as they can put a sort of amount of weight on the foot then I am not really worried until after they have lambed and in the short term.
Baz