Struts and Shocks

I have a 97 Dodge Grand Caravan SE with 157,000 miles and a 3 liter V6. I had the shocks and struts replaced and as I drove away from the shop I noticed that there was a very noticeable rattle apparently coming from the right strut every time I hit even a small bump. This rattle had not been there previously. I returned to the shop and had the mechanic ride with me around the block so that he could hear it for himself. He said he had heard it when he test drove it, but thought that the van must have been making that noise when I brought it in. He said he thought it might be a bad ball joint that I hadn't noticed because the suspension had been so poor. Is this a reasonable diagnosis, or do you think there is a problem with the struts and/or their installation? I don't think I have ever had any other front end work done on this vehicle. I am supposed to take it back by the shop tomorrow, and I would like to know if further car repairs could be justified.