No. Almost certainly what happened is that the image was being regenerated after being edited, and the dagger character (the + with a long tail) used was missing from the font on the system in question. Replacing a missing glyph with a question mark is a standard thing to do, on the basis that it's something people usually notice when proofreading... but unfortunately it isn't quite so obvious when the missing character occurs at the end of a sentence.
Never ascribe to malice that which can be adequately explained by incompetence, particularly where proofreading is concerned.
Actually, I similarly believe it was likely automatically recreated by a web app; and, since it's non-obvious, no employee has questioned it--but your insight is exactly what I was hoping for. I wanted to read some interesting thought processes from YC users, exactly like that, but couldn't think of a better way to relate it to startup news at the time.
If you visit http://www.dell.com/smb , you will see that Dell proudly states that they're the #1 PC of Choice in the US? (with a question mark.)
Google's cache shows a + at the end, instead of a question mark. Since this is an image file, and not text, how do you propose this happened? Surely, it's supposed to say ".. in the US+". The + reference still exists at the bottom of the live page...
There are a lot of hackers that are never caught. My credit card was stolen from what I think must be an online store that no one noticed had customer information stolen.. He bought three anonymous web proxy accounts with my CC on David Rusenko's non-Weebly company, in a weird coincidence.
Never ascribe to malice that which can be adequately explained by incompetence, particularly where proofreading is concerned.