Select max(id) causes AccessExclusiveLock?

On table

create table MyTableName (
id integer not null primary key,
seqYear char(4),
seqCount integer,
...)

Where id is primary key and (seqYear, seqCount) is a unique index.
Table facts: about 40 fields, 1 million records.

When I issue a

select max(id) from MyTableName

Postgres 9.2.7 is scaling a AccessExclusiveLock and causing large delays.

Is that expected? Is there a way to avoid the AccessExclusiveLock?

Thanks,

Edson