I own an stallion ( 4 yrs. old) and a gelding(9yrs. old) and get this the gelding does it more than the stallion. Go figure. Only think I can think of why the gelding does it is he was gelded late (at 3) and is older.
" I must not forget to thank the difficult horses, who made my life miserable, but who were better teachers than the well-behaved school horses who raised no problems." Alois Podhaisky, director of the Spanish Riding School 1939