Likewise. A quick scan returned negative results.
At the time I was reading a forum and hadn’t performed any action in several minutes other than scrolling the page down when the notice came up.
Here’s the URL the notification sent me to:
http://www.avast.com/en-us/lp-fr-virus-alert?p_ext=&utm_campaign=Virus_alert&utm_source=prg_fav_90_0&utm_medium=prg_systray&utm_content=.%2Ffa%2Fen-us%2Fvirus-alert-default&p_vir=Win32:Downloader-TJK%20[Trj]&p_prc=C:\Program%20Files\AVAST%20Software\Avast\AvastEmUpdate.exe&p_obj=http://files.avast.com/files/emupdate/20131217.exe&p_var=.%2Ffa%2Fen-us%2Fvirus-alert-default&p_elm=7&p_lex=120&p_lid=en-us&p_lng=en&p_lqa=0&p_lqe=0&p_lst=0&p_lsu=24&p_pro=0&p_bld=empty&p_vep=9&p_ves=0&p_vbd=2006&p_hid=60080564-0e61-4478-a460-1ef5447e6b53