I have had better luck with expired Wyeast packs vs. White labs. One tip though - don't make an overly large starter to put too much stress on the yeast and if the starter fermentation appears odd visually to you (or tastes/smells off) for whatever reason then don't use the yeast. Last summer I tried to start up two 1.5 mos past expiration date vials of WL 530 in a 1.5 L starter on a stir plate. I never saw a krausen or even any streaming bubbles of CO2 rising. But the wort was literally "spraying" (for better words) off the surface of the starter. The yeast did propagate, but when I pitched the ample starter into a low gravity patersbier (1.046) the resulting beer had some plasticy off-flavors I don't get in beers with healthy starters. Just my observations.