Google penalizes mobile sites that redirect to the home page for a mobile version....if you're not doing that, then you're likely not getting penalized.
One caveat: if your ads render wrongly on mobile devices, say you got some large rectangle ads which take the entire iphone screen, then you may face the traditional ads above the fold penalty... Remember, only google is allowed to spam the universe with their ads above the fold, YOU are not allowed to cash in on that delicious 20% CTR for ads.....