Thanks for letting us know,
Yes Wolfram|Alpha agrees with your figure of 3.32335... (maybe that is where you got?)
http://www.wolframalpha.com/input/?i=2.5%21
web2.0 calc
$${\mathtt{2.5}}{!} = {\mathtt{3.320\: \!382\: \!507\: \!505\: \!424}}$$
I don't know where else to look it up.
It is most likely a rounding error.
I will leave a note for admin.