Spot throw-in question

[zebraman]

Spot throw in. A1 inbounding ball and accidentally drops it and it rolls outside of the 3-foot wide area. A1 retrieves ball and returns to throw-in spot and completes throw-in within the five seconds. Would you call a violation or just blow the whistle (similar to a player losing the ball during a free throw attempt) and have a "do-over." Would it make a difference in how you handled it if B1 was applying inbounds pressure?

Thanks,

Z