I've just been suspended for high resource usage. I find this really hard to happen, since I'm a Prime member, and my Wordpress settings make it impossible for my blog to exceed the 64 MB limit.
The resource usage is not necessarily down to MB, it's down to the CPU and memory usage on the server. Some wordpress plugins cause these suspensions, particularly caching plugins. You may want to consider disabling any you may have, to see if it makes a difference.
I wouldn't worry too much, we find these issues come and go. If it happens again I can get someone to check some more specific details about the file(s) causing the issue.
The third warning is just a soft barrier, meaning your account is not permanently suspended after that but instead you just need to ask here to get someone to manually unsuspend it for you. It is basically a way of letting us know that you have a script that is repeatedly over the limit and should be checked out. Only the account managers have access to the list of scripts that caused the suspension, see we'll have to coax one in here to help you.
Thanks a lot!
My currently active plugins are:
-Akismet
-All in One SEO Pack
-Browser Sniff
-cforms
-FeedBurner Feedsmith
-Google XML Sitemaps
-MobilePress
-Official StatCounter Plugin
-Shockingly Big IE6 Warning
-Wordpress Database Backup
-WP-Ban
-WP-Memory-Usage
-WP-reCAPTCHA
-Yahoo/MSN Style Smilies