Tough question without knowing how the board was set up.

If you were holding down at least 2 notes, I wonder if it was interpreting the 3rd "tapping" note as a tension or suspended chord, and just resounding the root. This wouldn't be surprising if "Retrigger" was enabled on the bass track.

Also if the attack / sustain / release on the pad was sufficiently long, you might not have noticed that the board was trying to retrigger the pad notes as well.

I would love to see more demos of arranger players using their boards in this manner. In other words, triggering chords rubato with the style in pause. Adding multipads with chord match or stored sequences from a 2nd board or external module could make for a very interesting mix!