I'm almost certain that I've hit SO for more than 30 days in succession at this point, but I still haven't gotten my Enthusiast badge. I did do two things to my profile in this time period: I changed my display name on my profile, and I swapped my primary Open ID from a crappy old provider to Google. Could either of these have prevented me from getting the badge?
Name change: Doubtful. I've changed my Meta name several times, and am somewhat embarrassed to admit that I got my Fanatic badge (the gold variant of Woot, Enthusiast) yesterday for Meta.
The OpenID might, but I wouldn't know about that. Did you user ID number change when your OpenID changed? I'd think that the badges are tied to user ID, not OpenID. But I've been wrong before ...
Are you 100% sure you actually did visit the site, reloading pages and all, successively, whilst logged in? I actually e-mailed team@so over my Enthusiast badges for the Trilogy (since I'd gotten it on Meta first), and they're very certain the algorithms are working correctly -- sure enough, a few days afterward, my Woot (Enthusiast) badge appeared on SO.
This should no longer happen, as we respect (usually) the oldest user when merging. If it happens and you're missing the badge, post here on meta and I'll fire up a monster query that goes off and grants them for all time.
The default query for granting these runs against denormalized data and doesn't strictly respect each history record (but is very, very fast, it's a trade-off). Occasionally something happens and we go grant a few of these for users that were missed due to bad merges or some other crazy case.