The opening hours of the SKL SFO are tied to the departure times of SQ's flights. SQ wouldn't throw you out of the lounge before your flight departs, leaving you to cool your heals in the hallway or the RCC. The morning opening hours are linked to SQ 015/016, the SFO-ICN-SIN-vv. flights, the times of which get adjusted with daylight savings time. Since we're still on daylight savings, I'm sure the lounge will be on "summer hours." In any event, if you're just waiting for SQ 015 to depart, you've got nothing to worry about.