Well transits don't necessarily result in any effect - they are (or should) be seen as part of a system of prediction that requires several indicators of an event being produced. The transit's role being to fine tune the timing.
Secondly I'm surprised that you got an effect from Pluto/Vesta and I suspect that there was something else at work at that time but without seeing your chart I can't really give an indication as to what it could be.
Trines are 'weaker' than squares or oppositions and have the character of Jupiter (though despite being the 'greater benefic' that doesn't mean it's all sweetness and light).
Check to see what else is going on around the time of the Pluto transits - that really means looking at your solar returns, primary directions and secondary progressions, and other methods as well if you are interested.
