Tiger 955i Charging Question

[GRRR8!]

Hello friends, so I was about to get a new battery for the old girl and decided to make charging system check first. Using a multimeter, I connected to the battery terminal while the bike was idling and read 13.9V, as soon as I increase RPM over idle it drops down to about 12.5V. Might this indicate a bad Rectifier/Regulator or alternator?

Thanks for any input you might have,
Dan