Occassional Limping

My Zora is 6 months old and 5 weeks ago we thought her limp was from our friend stepping on her but she's been xrayed, no lymes but still she may limp -- you'd never know she has a problem with all the jumping she does and play she has but it's still there.

I was wondering if anyone else has experienced this with their Jack -- we ran into someone in New York City on the street who said their Jack does the same thing and it's just what they do, is it true? or do I need to pursue further?

Thanks