The main issue is still the misuse of executive power.
Not when the bill was created and became law. I'm pretty sure that was in 1993. She was in the state legislature from 2001-2007 before taking her current position in 2007. So, no, she wouldn't have been able to vote for the bill, but would have had plenty of opportunities to sponsor legislation to repeal or modify it.
This is why I think her taking offense to Perry's EO in Texas is a bit weak. I fully understand the argument against Perry issuing the EO rather than going to the legislature. That is very much a legitimate issue. Regarding Texas, the people didn't seem to mind it too much, as they voted him back into office for a 3rd time, with over 50% of vote in a 3 way primary, which included a very well financed and backed US Senator. The rest of the country is now hearing about it, so he's had to deal with it again. That's his consequence. Bachmann, however, overshadowed the issue by calling it Perrycare, saying it causes kids to become retarded, and that no governor OR legislature can mandate vaccines. That took away the issue of it just being a misuse or abuse of power by the governor, and made her look like she doesn't know the Constitution.
I do want to add that I like Michele Bachmann. She has been a solid conservative in DC. And I will openly state that I support Perry, if it isn’t already obvious. She does, however, run the risk of alienating a big chunk of the conservative base by going after Perry like this, when Jobs/Obama are the main issues. This may drag Perry down a notch, but I do not see it helping her campaign at all.