Prius c coil pack clip just won't click shut (but car runs fine)

I never thought I'd face a problem pushing in a lowly coil pack clip, but after changing spark plugs at 62,000 miles on daughter's 2013 Prius c, the last coil pack just would not *quite* go in enough to click shut. I looked at the clip fittings, male and female, nothing appears damaged or anything. It looks like it needs to push in about one more millimeter to click. I figured just to see how things run, I put duct tape to hold the clip in place (see cellphone pic). Everything appears to run fine, took the car on a short test drive and pushed it hard a bit, it's happy, no warning lights, etc. It seems peppier, maybe it's the new plugs, maybe it's my mind.

Anyway: has anyone experienced clips like this that just wouldn't click upon re-install? Logically it seems like it should be OK, with good contact made, but of course I don't like it.