That happens to me all the time on my double white, especially in the heat. I usually see the remnants of the dropped bud though sometimes it just disappears and I thought maybe the heat just dried them up.

When it starts to cool down at night, I get a lot more blooms fully open.

My plants are drooping buds like crazy. Very few of my brugs are holding onto their buds. Like ROD said it's most likely attributed to high temps. Even when my plants are evenly watered they still drop during high temps. Once the evening temps start cooling down the buds begin to hold.

thanks y'all,guess i'll see more when it gets a little cooler.just can't figure where the buds went.

Maybe a breeze blew them away? If they were small they likely discolored and shriveled up so much that you wouldn't easily be able to find where they dropped or an insect might have eaten a fallen bud.