I did the google search as you suggested, and I see your point.
In defense of my design:
1. It's multi colored (everything google image search threw up was mono-chrome)
2. I don't have the stem in the picture
3. None of the shirt designs show up when you don't include shirt in the image search (which is what I did when looking for references)
Given the fickle nature of the rejectionator, I've come to the conclusion you're better off submitting and see what happens then self censoring.
Just look what's happening in the fog right now. In my opinion the jet pack shirt should have bit the dust days a go, while the ET shirt was different enough from existing designs to stay. I have very little doubt there is personal bias at work when it comes to rejections.
