You've got nothing to worry about. I'd be willing to bet you can swap any slide onto any other LC9 frame and have it work fine. Providing they're both in good condition.I have an earlier serial number LC9 with a front sight slightly off center, causing impacts a little to the left. I understand that newer LC9s come with the sight pinned in place, and so I called Ruger to ask them about it. They are very generously sending me a new slide and a return envelope to ship back the old one.
This got me to thinking about how particular parts wear in together, and now I'm wondering if there could be any adverse affects with matching a new slide with a frame and barrel that have about 1000 rds on them?