I had four switchlincV2's do this as well. I found that removing the paddle putting a tiny tiny dab of hot glue on the tips of the posts that make contact with the microswitches (and letting them dry) seemed to do the trick for a while. (I tried this on one switch, but in the end it wasn't worth the hassle). Removing the paddle and pushing the microswitch directly was reliable 100% of the time.
I think the posts are a tiny bit short and are enough to make the metal button go click, but are just not quite enough to make electrical contact in some circumstances. I'd suspect bathroom oxidation, but we had one dimmer do the same thing *AS SHIPPED* from smarthome (directly out of the box), before the decora plate was even installed.
I had a couple of them do this and they drove my wife crazy as they were in high traffic areas (both bathrooms!). Sometimes, it would take 10+ pushes/wiggles/etc to make them finally turn on or off. They WOULD respond to remote control (eg: the nearby keypadlincV2).
I don't remember what we did with the bathroom ones. It was months ago. I'm pretty sure I returned those two, but it was possible I used them as paddle-less appliancelincV2 replacements.
(In case anybody was wondering, I do NOT return anything I've modified as that is clearly a warranty void situation!)
In any case, the failure mode made me a bit nervous. I resolved to check all the infrequently used switchlincV2's about once a month, just in case any more are going.