Yes and no. NEXFAIL does that to scare you sometimes, But other times, They actually will take action. I say don't worry about it if you don't have stupid stuff (NX and stuff) on that account. If not, you should worry and pray about it. I've had that once also but my account hasn't been banned. Here's something you should know about "NEXFAIL is pretty slow with banning and fixing stuff"
It's kinda like what happened to my ipod "LIES"