What was your glycerin/water/yeast ratio? I just froze some yeast (wlp029) and I unfroze one after 2 weeks and it took off after 1 day, but 13 months is good to hear. I mixed 5 ml of 15% glycerin/water with 5 ml of thick yeast slurry.
I have been harvesting and reusing my yeast since I started brewing. I only buy yeast at this point when I try new styles. But I now have many, many more mutchkins of yeast in my fridge than I can brew firkin of beer. I'll have to lookinto this more closly.
I so love pitching a pint of yeast in my wort and having it go at it only hours later.