security - I think that I may have been a victim of a malicious mms

I have a Sidekick 4g running Android 2.2.1.

I just received a multimedia message from an acquaintance who I happened to have in my contact list. I clicked on the notification which sent me to something that looked like a twitter login screen and then it went away and went to my home screen. I immediately turned my phone on airplane mode (in case my phone was just turned into a spam machine) and went to my messages to look at the message again, but it was gone which gives me even more fear that my phone is infected with something.

Is there a known vulnerability in android that can infect my phone without any action on my part other than viewing a message? If so, how can I eradicate it?

Edit

I do have unknown sources turned on. I downloaded a permissions-checker app and have nothing unusual requesting to send mms, but is only beneficial if it is not a 0-day. I checked my t-mobile account and it said that I have only sent one sms this month.

TL;DR

Received mms, think my phone is now infected w/ trojan.