Unknown sender text, what about Stagefright?

I use 8sms as my default text app. In the Google Messenger app I see a text of 829 bytes from an unknown sender yesterday which I have not downloaded. This text is not seen in my 8sms messaging app, nor is it seen in the mysms app. Is there any way to check this message outside of my phone? I don't want to open it given the circumstances, but I don't want to miss a legit text.