Odd Signal Sound and Display

I might be completely ignorant by asking this question, but what does it mean when the V1 displays a signal but does not say what type of band it is? The sound is also different than the other bands. It is a very short single 'scratchy sounding' 'DENT' (sorry for my lack of V1 sounds speak). I have K and X turned off.

Most of the time I can find another car floating around me with a detector that seems to look like a cheap model of some sort. It is always a very faint single-dot signal on the display. I always assumed it was a radar signal from other detectors.

I can't find any mention of this in the manual or on the forums. Am I just going crazy?

Yup, either you're nuts or the V1 is in need of a fix.

If you have Ku band enabled you may be picking up a false Ku band alert. No dots will light up on the bands but a small dot ( . ) appears in the lower right corner of the bogey counter