We have an oil-fired hydronic heating system. The boiler is approximately 30-40 years old, and the system was checked and cleaned at the start of this winter. When the burner is running, you can hear it from the first floor. We've noticed that sometimes, after running for a few minutes, the burner will shut off for one or two seconds, and then immediately start up again.
This behavior doesn't really make sense to me, but I'm not sure if it's just a quirk or an indication of a problem. What could be causing the shutoff and then immediate re-ignition? Should we check it out or just stop worrying?