I launched my app using IOS 6.1, will that lock me out of potential customers?

I launched my app using IOS 6.1, will that lock me out of potential
customers?

I would just like to ask a quick question. I have recently launched my app
requiring IOS 6.1, It was the latest setting and I thought it will make my
game more compatible with Iphone 5. However, as my game was approved and
is now up for sale in itunes, i notice that I'm practically the only one
(or one of a few) that requires IOS 6.1.
Most of the major players especially only require IOS 4.3 or IOS 5.0. That
makes their games applicable even to non-IOS 6.1 phones. Does this mean
that if a potential buyer hasn't yet updated his phone to IOS 6.1 he will
not be able to use my app?
Did I just make a HUGE marketing mistake? Should I have launched my app
with a much lower IOS minimum requirement?
How about you guys. Do you make your apps using the latest IOS SDK or make
them using lower SDKs to appeal to a greater market?
Thanks for those who can give an insight.