RepeatEvery within OnAlarm fires immediately without taking into consideration of the wait time

If the onAlarm has repeatEvery with a wait time, it gets fired without waiting for the duration specified when it gets executed in the first iteration.

<bpel:onAlarm>
<bpel:repeatEvery>"PT15S"</bpel:repeatEvery>
<bpel:scope name="SubProcess-1" > </bpel:Scope>
</bpel:OnAlarm>

If we look at the EH_ALARM.java especially the run method,

if (_oalarm.forExpr != null)

{ calculate wait time }else if (_oalarm.untilExpr != null){ calculate wait time }

// We reduce to waiting for the alarm to be triggered.
instance(new WAIT(alarm));

We can see that there is a check for "for" expression and "until" expression but not for "repearEvery" expression.

Shouldn't repeatEvery wait for 15 seconds as specified in the above
example when it gets executed during the first iteration?