An opto-coupler/triac oddity -- is it a problem, and is there a solution?
I suspect the issue here is that the triac part of the VO2223A is triggering due to a transient pulse at its input which occurs when turning on your main power switch.  With ordinary triacs, the general problem of transients triggering triacs is treated with what's called a "snubber network".  I assume the problem would also occur in an optocoupler triac too, even though it doesn't have a gate wired up.

This application note describes the problem, with some example solutions. http://www.fairchildsemi.com/an/AN/AN-3008.pdf. (You can probably google for other sources on this same topic, and there may be app notes that pertain specifically to optocoupled triacs).

One item that the paper mentions is that the problem is worst when the triac starts off in the state where no power is applied, as that is when the "collector to gate" (in the 2-transistor equivalant model) capacitance is greatest, and thus quite effectively couples the pulse from you turning on the switch into the gate, turning on the triac, at least for one half cycle.

I would not expect this to harm the devices, as this is just "normal operation" albeit for a very short time.