Old rice does indeed tend to dry out and cook up firm rather than sticky (http://news.curiouscook.com/2007/02/rice-scented-and-un-old-and-new.html), so if the cooking-time adjustment doesn't help, tweaking the soak-time/water level may be needed.

And I've only ever seen the microwave-insta-serv-rice in shortgrain (http://www.amazon.com/Shirakiku-Instant-Cooked-Rice-Pk/dp/B000643THQ/ref=pd_sim_gro_1) around here, but that's from shopping at Korean and Japanese markets -- I'd imagine non-Asian supermarkets might be more likely to stock similar products in long-grain.