When is it Granted--time-out

[som44]

Situation last night in a boys JV game--my partner (unpatched) blew his whistle and said time out blue when in fact blue was not able to call a time-out. Ball was in possession of the other team. I realized this immediately but was not sure of what to do. Case book 5.8.3 says they are still entitled to the time out since it was granted. here is my question--I realized his mistake before he reported it but after he blew his whistle and said "time-out blue" When is a time-out considered granted? Could i just have spoken to him quickly gone with an inadvetent whistle and given the ball back to the other team for a throw-in or was i correct in allowing the time-out.