Yeah. I kinda see that now that I'm looking at it closer on my iPad instead of my phone. It really shouldn't put any undue stress on the 510 though. The way the ProVaris set up, the connection is extremely solid. Now, the 510-eGo adapter and base of the MT3 might be a different story.
As an out of pocket configuration I also wouldn't worry, but I'm a little concerned that with the potential for that much play it might cause damage to the Provari's 510 connector over time when subjected to the lateral forces caused by carrying it in your pants pocket.
I'm really considering a Provari, but almost exclusively use Kanger products (T3, evod, protank). The only thing holding me back is worrying if it will hold up to my pocket "abuse" with these
devices attached. I really wish Provape would offer a native ego style connection or a ring that would tighten things up when an adaptor is used.