Not only that, but it seems to me that Yoshi is a bit.. glitchy in the juice area (for lack of a better word): I've stood perfectly still before, and Yoshi's juice gauge will randomly jump from being half-full to near the top, and back down to about where it was (I think it was most notable on purple Yoshi, but I could be wrong).
I don't know if that's just what it did normally when Yoshi was running low on juice or if I just never noticed, but it stuck me as odd.