MySQL update errors with "Subquery returns more than 1 row" despite lack of subquery

Question

I have a query on mysql 5.1.56:

select * from team_member_accounts where node = 33136

...that returns exactly one row. However, the following query errors with Subquery returns more than 1 row:

update team_member_accounts
set fee_remaining = 0,
    loan_account_balance = 35000,
    reimbursable_amount = 0, 
    reimbursed_amount = 0
where node = 33136

Um...what? What subquery? And how is it more than one row?

Answer 1

The table likely has a trigger.