Could it be this years new growth encouraged by all this rain to be extra vigorous?

Where are the long shoots coming from? I'm just wondering if you mean suckers...

That's what lilac bushes do though isn't it?

I have a lilac bush and there are no long shoots on mine, I have some new growth about 1-2 inches long.

Yes, Pam, they do - one of the reasons I never plant them, all those suckers, pain in the proverbial

I have some growing right up next to my fence from next door, always pulling shoots out which have crept along under the fence hoping to find fresh growing space, not on my patch though!!!:))

Rare for lilacs to be grafted, though. John, if it is a young plant, thes will probably be the future structure of the tree, producing branches of their own, which should bloom in 2014. Also, bushes in the shade will send out long, spindly stems toward the nearest sun, in an attempt to get enough energy to bloom.