No real idea here but a couple of thoughts. One would not think a one year old battery would be bad but you never know. Can you check it with a volt meter? With the key off and setting for a while the battery should measure around 12.7 If not battery is suspect. When strarted and running long enough to charge the battery it should measure around 14 volts. If not charging system is suspect.
some other thoughts, you bought the bike used, so could someone have installed an accessory that draws current with the key off? Would it be possible you had enought accessories on and maybe ran slow last ride not charging the battery? I believe the generator is 33 amps at 5,000 RPM. If you ran at half RPM with lots of stuff on maybe you did not charge the battery.
Guess you will know next time it sits. Good luck.