Anyone else have this issue?

When testing the clock module, I saw a good bit of noise when pressing the clock step button. The problem seemed to stem from holding the button down too long. To test this, I held the button down while watching the clock output on my scope. Initially, there would be no noise until the threshold cap on the debounce 555 timer discharged, then immediately, significant high frequency noise would appear. Making the threshold cap value larger would delay the issue (but would make the debounce delay longer as well, of course).

Adding a small ceramic cap between the output pin and ( ) on the debounce 555 timer seems to have resolved the issue.

I assume the problem is that the debounce timer is charging/discharging rapidly, creating high frequency switching noise when the button is held down. Perhaps this is due to the additional capacitance in the breadboard messing with the debounce circuit? Thoughts?