A tricky call to make in the first 60 seconds

My local team Maidstone United in action on Tuesday night and a very good spot from the referee to allow this first minute goal. From the throw, the ball cannons around before bouncing off the head of a Blue defender to a Maidstone player who taps the ball in.

The Maidstone player is in an offside position and the assistant flags - quite correctly - for offside because he has presumably not seen who got the last touch.
The referee has spotted the sequence of events and is able to allow the goal, as the ball was played to the scorer by a defender, meaning he is not offside.
Kudos to the ref, who has to sell a very tricky decision in the first 60 minutes. He quite rightly consulted the assistant, seemingly advising him that the ball had reached the Maidstone attacker from a Blue defender.