I've got some bottles of yeast I saved from prior batches (siphon the yeast cake into a 12oz bottle and cap it). One is Wyeast London III #1318, the other is White Labs German Lager. They have been in the fridge for about 6 months now. The batches they came from went fine, so at least at the time they were healthy. Is it worth making a starter and seeing if they are still viable? I have used this yeast storage technique after a month or two and it works fine, but never tried pushing it this far.