MySQL Deadlock Issue (2 replies)

I insert one row on table t1 (innoDB engine) and there is one trigger on after insert event.
In trigger, i fetch data using select statement in same table like "SELECT * FROM t1 WHERE ID = NEW.ID".
It works perfectly 2-3 months. but now it gives Deadlock issue.
what is reason behind it ?
is it possible while multiple thread access same operation on same table at a time ?