Plugs and wires look fine, but maybe one has become dislodged? I would pull them off at each end and reconnect. The guys at the shop shouldn't have touched the wires, but who knows?
If you can get the code pulled, it should tell you which cylinder the misfire is occuring in, like this: P030x. For example, if its cylinder 5, you'll get a P0305. This will at least help you narrow down the source of the misfire.
