Not a lot of info but this usually just means that the flight was held waiting for an arrival slot to be assigned at SFO. This is quite common during any kind of cloudy or foggy weather when they institute a traffic management program:
Code:
1840/20FEB
P PHX/OUT 921P L04.56 ☨
P PHX/OFF 933P
P SFO/ETA 1032P L05.00 AIR TRAFFIC CONTROL
D CRC/SFO/ POSS DLYS/CNCL DUE TO STRONG WINDS-RAIN
D HDQ/PHX SFO PROT UNDER GG CN2 T66
SKED PHX ORIG 425P GTD 6B SHIP 3446
SFO 532P TERM GTA 90