The reason why I noticed it this past week is because there was a discrepancy of 6 minutes! 

Depending on the week, it varies by more than 1-2 minutes

I downloaded the calendar directly from Hebcal into Google Calendar for my zip code (11210), so in theory, they should be exactly the same.

July 3: Hebal is 8:12 and Google calendar is 8:13, so it's late by 1 min
July 10: Hebal is 8:09 and Google calendar is 8:11, so it's late by 2 mins
July 17: Hebal is 8:05 and Google calendar is 8:11, so it's late by 6 mins
July 24: Hebal is 8:00 and Google calendar is 8:03, so it's late by 3 mins
July 24: Hebal is 7:53 and Google calendar is 7:55, so it's late by 2 mins