That would just be the Power LED, which only means that your system is turned on.
Blowing air through the PSU shouldn't have done anything bad to it, though who knows. If your really concerned, you could open it up and have a look. Do not mess with or touch anything inside, the capacitors in PSU's can hold a lethal charge even months after last being plugged in. Your pretty much just looking to see if there is anything obviously wrong with it.