Yes, this is normal because you need to scan your computer regularly in order to keep it safe and clean from malware. So when you don't scan your system for a few days, it pops up a warning. Just do a quick scan whenever you get this message and everything should be fine. Hope it helps!Kunal D Mehta - a Windows Server Enthusiast.

I do a scan using security essentials, do other things and suddenly the orange icon warning me that my computor is at risk that a scan has not beem done for some time, this is happening quite often