I think for whatever reason...tonight it bothered her...not necessarily has progressed any worse. If it had...I think you would see symptoms of it bothering her more. Ramsey has mild LP...but she has instances like you just describe. Sometimes I know what's caused it...like renting a beach house with lots of stairs. If I don't carry her up and down...before the 3rd day..she will be noticeably limping. After a few days of no stairs...she no longer limps.
I'd suggest watching her...but I know you're already doing that.
If you see her continuing to favor it...then it may be time to have it reevaluated.