V3 w/Extra024s9 and hall-dizzy middle-LED question

[berlina2000]

I've got a V3 with MSnS-E 024s9 code hooked to a bosch hall dizzy. When testing the function of the dizzy connected to MS I found that works like it should (using a 1K from proto area 5v to tachselect-optoin jumper). The middle LED lits up when metal is the gap of hall-sensor(using FIdle as spark output). If I then stop rotating the dizzy and leave a metal finger in the gap of the hall, the middle LED stays lit for a few second and then goes to a somewhat weaker, kind of flickering state. The same happens if I just ground pin 24 without the dizzy. Also the same happens to my other MS V3 when putting 12v or 5v on pin 24(there's no 1K installed).
Is that normal? and if so, how come? I can't remember my earlier V2.2 boards behave like that using the same code.