Or at least there was when I got up this morning. I have since rescued the little guy and set him free in my front yard.
My GQ’s are:
Did the frog get in through the pipes in the house?
Or did he most likely get in some other way?
Is there something I can do to prevent “frog intrusions” in the future?
The wife gets real freaked by wildlife in the sink 
Mars
Tree frong can climb sheer surfaces with their sticky foot pads. tree frogs tend to be small. It sounds like this could be one.
Any open window in the kitchen last PM?
Any small boys in the house? I know I’d have tried to keep a frog in the sink, if I could have gotten away with it.
Hmmm.
No open windows I know of, and definitely no children of any kind.
The frog was about 3 inches in length and light brown in color. He was sitting in an empty bowl which had held strawberries the night before.
*Fresh strawberries? That you, maybe, brought in from your or a neighbor’s garden?
No, fresh from the store.
So it is likely that I let the critter in somehow, and not that it crawled up the drain pipe?
Drain pipes have “U” bends in 'em.
Bets he had help.
If you live near a creek it may have jumped in when the door was open. My aunt had a similar thing happen to her, except it was a crab that had gotten out of a basket on the porch.
He could have climbed down the vent pipe. The next question would be, how did the frog get onto the roof?
He’s a frog, he jumped. That was easy. 
Did you take the bones out?
If you hang your clothes outdoors, he may well have hitched a ride with them when they were brought into the house. Having escaped the clothes basket he would have then headed for somewhere wet and cool, showers, sinks, toilets. In australia it is not uncommon to, when flushing the toilet, see the bodies and legs of small treefrogs holding on for dear life under the rim!