Could he really of been gelded at 4?

so i looked at my geldings passport which was issued july 2010 and it says he is 'entire'. he came from a racing stud. could he really of been gelded at 4 and still act like a gelding? he is so docile most all of the time. he does sniff up mares bums sometimes but doesnt really do anything its more of a interested sniff. he is also out at the moment with a mare would he act diffrently when she is in season if he was gelded last year? could it all be a misprint?