pt-heartbeat 2.1.8 reports big time drift with UTC_TIMESTAMP

I just noticed pt-heartbeat is now using UTC_TIMESTAMP with the check/monitor query, for updates by older version and check by 2.1.8 or vice versa, there will be a large time delay reported. See a snippet of debug output below:

This is 2.1.8:

# $DBD::mysql::VERSION: 4.013 $DBI::VERSION: 1.609
# pt_heartbeat:4904 16322 Heartbeat row primary key: server_id = 1
# pt_heartbeat:4910 16322 SELECT 1 FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:5048 16322 SELECT SQL: SELECT UNIX_TIMESTAMP(UTC_TIMESTAMP()), UNIX_TIMESTAMP(ts)/*!50038, @@hostname AS host*/, server_id FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:5055 16322 SELECT UNIX_TIMESTAMP(UTC_TIMESTAMP()), UNIX_TIMESTAMP(ts)/*!50038, @@hostname AS host*/, server_id FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:5057 16322 Heartbeat from server 1
# now: 1358235876
# ts: 1358217876
# skew: 0.5
# pt_heartbeat:5062 16322 Delay 17999.500000 on forge.dotmanila.com
# pt_heartbeat:5103 16322 --check and exit
# pt_heartbeat:5234 16322 Checking slave delay
# pt_heartbeat:5274 16322 Checking slave D=test,S=/tmp/mysql_sandbox5091.sock,h=localhost,p=...,u=msandbox
# pt_heartbeat:5284 16322 Woke up at 2013-01-14T21:44:37.501070
# pt_heartbeat:5055 16322 SELECT UNIX_TIMESTAMP(UTC_TIMESTAMP()), UNIX_TIMESTAMP(ts)/*!50038, @@hostname AS host*/, server_id FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:5057 16322 Heartbeat from server 1
# now: 1358235877
# ts: 1358217877
# skew: 0.5
# pt_heartbeat:5062 16322 Delay 17999.500000 on forge.dotmanila.com
17999.50
# pt_heartbeat:5329 16322 Disconnecting

This is 2.1.7

# $DBD::mysql::VERSION: 4.013 $DBI::VERSION: 1.609
# pt_heartbeat:4822 16328 Heartbeat row primary key: server_id = 1
# pt_heartbeat:4828 16328 SELECT 1 FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:4940 16328 SELECT SQL: SELECT ts/*!50038, @@hostname AS host*/, server_id FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:4947 16328 SELECT ts/*!50038, @@hostname AS host*/, server_id FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:4950 16328 Heartbeat from server 1
# now: 2013-01-14T21:45:28.657450
# ts: 2013-01-14T21:45:28.000600
# skew: 0.5
# pt_heartbeat:4955 16328 Delay 0.156854 on forge.dotmanila.com
# pt_heartbeat:4996 16328 --check and exit
# pt_heartbeat:5127 16328 Checking slave delay
# pt_heartbeat:5167 16328 Checking slave D=test,S=/tmp/mysql_sandbox5091.sock,h=localhost,p=...,u=msandbox
# pt_heartbeat:5177 16328 Woke up at 2013-01-14T21:45:29.500810
# pt_heartbeat:4947 16328 SELECT ts/*!50038, @@hostname AS host*/, server_id FROM `test`.`heartbeat` WHERE server_id='1' LIMIT 1
# pt_heartbeat:4950 16328 Heartbeat from server 1
# now: 2013-01-14T21:45:29.501140
# ts: 2013-01-14T21:45:29.001320
# skew: 0.5
# pt_heartbeat:4955 16328 Delay -0.000180 on forge.dotmanila.com
0.00
# pt_heartbeat:5222 16328 Disconnecting

This should at least be documented if not made aware of the ts offset that generated the ts on the master.