Yes, but my N900 tells me this with a different message.
Says something about "The Phone is using more Power than the Charger delivers. Use original charger"

Why is the N900 following those USB Guidelines so strict? Ive seen USB devices doing whatever they like, ive seen USB Ports on my powered Hub going offline (the HUB switched the port offline, not the device connected to it) because the device connected pulled too much power.
Even modern, brand labled devices are often using more power than allowed by the specs (most USB-HDDs wich can be powered via USB, for example)

But the N900 doesnt do that. It even negotiates the power it may take with the Computer. (It has to do this, according to specs. But the mentioned USB-Drives usually dont do this. it would prevent booting from them, though)
I mean, usually its a good thing if a Vendor followes specs, but "someone" should develop an app to override these settings *g*