Besides a sore tummy? No.

I've got datura (the old west "loco" or jimson weed) and belladonna all over under mine tho so keep 'im away from my place ok?

does he sleep well afterwards? Passion flower is supposed to have sedative affects.

~Chills

My dogs have been eating passion flowers for years. So far no ill effects other than when they fight over a choice flower.

Passiflora protects itself with cyanide in its tissues, some have more than others. As far as I can tell it's to make the caterpillars that eat the leaves poison so birds will leave them alone. The cyanide appears to be strongest in leaves and unripe fruit, but I think there must be very little in the flowers or my dogs wouldn't be so fond of them. They don't seem to enjoy the leaves particularly but will chew on stems, sometimes.

A bit more info here re toxicity.
See http://www.passionflow.co.uk/butt.htm
& link below.

Here is a link that might be useful: Passiflora txicity

If you want to discourage him, boil some hot pepper in a couple of cups of water, and spray it on the vine at the level he can reach it. One or two munches and he will give that up quickly. Works for cats on houseplants too...