muse hits the proverbial sub on the tail, (to paraphrase)

Too submissive for one dom may well be not enough for the next. So just follow your new master's lead. And don't be afraid to ask how you're doing? Ask him "Is master happy with his ________" (fill in your own sub-word.)

Me? I personally hate brats and love subs. I don't want a "broken spirit" mind you. I like spirit. I like it applied in spirited service to my desires. So, no, you can't be too submissive... you just need to know what your master expects and wants from you.